Begin: WIP consistent Begin/End behavior, ListBoxHeader() fix.

# Conflicts:
#	backends/imgui_impl_win32.cpp
#	imgui.cpp
#	imgui_demo.cpp

.gitignore

@@ -34,7 +34,7 @@ xcuserdata
 examples/*.o.tmp
 examples/*.out.js
 examples/*.out.wasm
-examples/example_emscripten_opengl3/web/*
+examples/example_emscripten_opengl3/example_emscripten_opengl3.*
 
 ## JetBrains IDE artifacts
 .idea

LICENSE.txt

@@ -1,6 +1,6 @@
 The MIT License (MIT)
 
-Copyright (c) 2014-2021 Omar Cornut
+Copyright (c) 2014-2020 Omar Cornut
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal

backends/imgui_impl_dx10.cpp

@@ -2,7 +2,8 @@
 // This needs to be used along with a Platform Backend (e.g. Win32)
 
 // Implemented features:
-//  [X] Renderer: User texture backend. Use 'ID3D10ShaderResourceView*' as ImTextureID. Read the FAQ about ImTextureID!
+//  [X] Renderer: User texture binding. Use 'ID3D10ShaderResourceView*' as ImTextureID. Read the FAQ about ImTextureID!
+//  [X] Renderer: Multi-viewport support. Enable with 'io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable'.
 //  [X] Renderer: Support for large meshes (64k+ vertices) with 16-bit indices.
 
 // You can copy and use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
@@ -11,6 +12,7 @@
 
 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
+//  2020-XX-XX: Platform: Added support for multiple windows via the ImGuiPlatformIO interface.
 //  2019-07-21: DirectX10: Backup, clear and restore Geometry Shader is any is bound when calling ImGui_ImplDX10_RenderDrawData().
 //  2019-05-29: DirectX10: Added support for large mesh (64K+ vertices), enable ImGuiBackendFlags_RendererHasVtxOffset flag.
 //  2019-04-30: DirectX10: Added support for special ImDrawCallback_ResetRenderState callback to reset render state.
@@ -57,6 +59,10 @@ struct VERTEX_CONSTANT_BUFFER
     float   mvp[4][4];
 };
 
+// Forward Declarations
+static void ImGui_ImplDX10_InitPlatformInterface();
+static void ImGui_ImplDX10_ShutdownPlatformInterface();
+
 static void ImGui_ImplDX10_SetupRenderState(ImDrawData* draw_data, ID3D10Device* ctx)
 {
     // Setup viewport
@@ -501,6 +507,7 @@ bool    ImGui_ImplDX10_Init(ID3D10Device* device)
     ImGuiIO& io = ImGui::GetIO();
     io.BackendRendererName = "imgui_impl_dx10";
     io.BackendFlags |= ImGuiBackendFlags_RendererHasVtxOffset;  // We can honor the ImDrawCmd::VtxOffset field, allowing for large meshes.
+    io.BackendFlags |= ImGuiBackendFlags_RendererHasViewports;  // We can create multi-viewports on the Renderer side (optional)
 
     // Get factory from device
     IDXGIDevice* pDXGIDevice = NULL;
@@ -518,11 +525,14 @@ bool    ImGui_ImplDX10_Init(ID3D10Device* device)
     if (pDXGIAdapter) pDXGIAdapter->Release();
     g_pd3dDevice->AddRef();
 
+    if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+        ImGui_ImplDX10_InitPlatformInterface();
     return true;
 }
 
 void ImGui_ImplDX10_Shutdown()
 {
+    ImGui_ImplDX10_ShutdownPlatformInterface();
     ImGui_ImplDX10_InvalidateDeviceObjects();
     if (g_pFactory) { g_pFactory->Release(); g_pFactory = NULL; }
     if (g_pd3dDevice) { g_pd3dDevice->Release(); g_pd3dDevice = NULL; }
@@ -533,3 +543,124 @@ void ImGui_ImplDX10_NewFrame()
     if (!g_pFontSampler)
         ImGui_ImplDX10_CreateDeviceObjects();
 }
+
+//--------------------------------------------------------------------------------------------------------
+// MULTI-VIEWPORT / PLATFORM INTERFACE SUPPORT
+// This is an _advanced_ and _optional_ feature, allowing the backend to create and handle multiple viewports simultaneously.
+// If you are new to dear imgui or creating a new binding for dear imgui, it is recommended that you completely ignore this section first..
+//--------------------------------------------------------------------------------------------------------
+
+// Helper structure we store in the void* RenderUserData field of each ImGuiViewport to easily retrieve our backend data.
+struct ImGuiViewportDataDx10
+{
+    IDXGISwapChain*             SwapChain;
+    ID3D10RenderTargetView*     RTView;
+
+    ImGuiViewportDataDx10()     { SwapChain = NULL; RTView = NULL; }
+    ~ImGuiViewportDataDx10()    { IM_ASSERT(SwapChain == NULL && RTView == NULL); }
+};
+
+static void ImGui_ImplDX10_CreateWindow(ImGuiViewport* viewport)
+{
+    ImGuiViewportDataDx10* data = IM_NEW(ImGuiViewportDataDx10)();
+    viewport->RendererUserData = data;
+
+    // PlatformHandleRaw should always be a HWND, whereas PlatformHandle might be a higher-level handle (e.g. GLFWWindow*, SDL_Window*).
+    // Some backends will leave PlatformHandleRaw NULL, in which case we assume PlatformHandle will contain the HWND.
+    HWND hwnd = viewport->PlatformHandleRaw ? (HWND)viewport->PlatformHandleRaw : (HWND)viewport->PlatformHandle;
+    IM_ASSERT(hwnd != 0);
+
+    // Create swap chain
+    DXGI_SWAP_CHAIN_DESC sd;
+    ZeroMemory(&sd, sizeof(sd));
+    sd.BufferDesc.Width = (UINT)viewport->Size.x;
+    sd.BufferDesc.Height = (UINT)viewport->Size.y;
+    sd.BufferDesc.Format = DXGI_FORMAT_R8G8B8A8_UNORM;
+    sd.SampleDesc.Count = 1;
+    sd.SampleDesc.Quality = 0;
+    sd.BufferUsage = DXGI_USAGE_RENDER_TARGET_OUTPUT;
+    sd.BufferCount = 1;
+    sd.OutputWindow = hwnd;
+    sd.Windowed = TRUE;
+    sd.SwapEffect = DXGI_SWAP_EFFECT_DISCARD;
+    sd.Flags = 0;
+
+    IM_ASSERT(data->SwapChain == NULL && data->RTView == NULL);
+    g_pFactory->CreateSwapChain(g_pd3dDevice, &sd, &data->SwapChain);
+
+    // Create the render target
+    if (data->SwapChain)
+    {
+        ID3D10Texture2D* pBackBuffer;
+        data->SwapChain->GetBuffer(0, IID_PPV_ARGS(&pBackBuffer));
+        g_pd3dDevice->CreateRenderTargetView(pBackBuffer, NULL, &data->RTView);
+        pBackBuffer->Release();
+    }
+}
+
+static void ImGui_ImplDX10_DestroyWindow(ImGuiViewport* viewport)
+{
+    // The main viewport (owned by the application) will always have RendererUserData == NULL here since we didn't create the data for it.
+    if (ImGuiViewportDataDx10* data = (ImGuiViewportDataDx10*)viewport->RendererUserData)
+    {
+        if (data->SwapChain)
+            data->SwapChain->Release();
+        data->SwapChain = NULL;
+        if (data->RTView)
+            data->RTView->Release();
+        data->RTView = NULL;
+        IM_DELETE(data);
+    }
+    viewport->RendererUserData = NULL;
+}
+
+static void ImGui_ImplDX10_SetWindowSize(ImGuiViewport* viewport, ImVec2 size)
+{
+    ImGuiViewportDataDx10* data = (ImGuiViewportDataDx10*)viewport->RendererUserData;
+    if (data->RTView)
+    {
+        data->RTView->Release();
+        data->RTView = NULL;
+    }
+    if (data->SwapChain)
+    {
+        ID3D10Texture2D* pBackBuffer = NULL;
+        data->SwapChain->ResizeBuffers(0, (UINT)size.x, (UINT)size.y, DXGI_FORMAT_UNKNOWN, 0);
+        data->SwapChain->GetBuffer(0, IID_PPV_ARGS(&pBackBuffer));
+        if (pBackBuffer == NULL) { fprintf(stderr, "ImGui_ImplDX10_SetWindowSize() failed creating buffers.\n"); return; }
+        g_pd3dDevice->CreateRenderTargetView(pBackBuffer, NULL, &data->RTView);
+        pBackBuffer->Release();
+    }
+}
+
+static void ImGui_ImplDX10_RenderViewport(ImGuiViewport* viewport, void*)
+{
+    ImGuiViewportDataDx10* data = (ImGuiViewportDataDx10*)viewport->RendererUserData;
+    ImVec4 clear_color = ImVec4(0.0f, 0.0f, 0.0f, 1.0f);
+    g_pd3dDevice->OMSetRenderTargets(1, &data->RTView, NULL);
+    if (!(viewport->Flags & ImGuiViewportFlags_NoRendererClear))
+        g_pd3dDevice->ClearRenderTargetView(data->RTView, (float*)&clear_color);
+    ImGui_ImplDX10_RenderDrawData(viewport->DrawData);
+}
+
+static void ImGui_ImplDX10_SwapBuffers(ImGuiViewport* viewport, void*)
+{
+    ImGuiViewportDataDx10* data = (ImGuiViewportDataDx10*)viewport->RendererUserData;
+    data->SwapChain->Present(0, 0); // Present without vsync
+}
+
+void ImGui_ImplDX10_InitPlatformInterface()
+{
+    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
+    platform_io.Renderer_CreateWindow = ImGui_ImplDX10_CreateWindow;
+    platform_io.Renderer_DestroyWindow = ImGui_ImplDX10_DestroyWindow;
+    platform_io.Renderer_SetWindowSize = ImGui_ImplDX10_SetWindowSize;
+    platform_io.Renderer_RenderWindow = ImGui_ImplDX10_RenderViewport;
+    platform_io.Renderer_SwapBuffers = ImGui_ImplDX10_SwapBuffers;
+}
+
+void ImGui_ImplDX10_ShutdownPlatformInterface()
+{
+    ImGui::DestroyPlatformWindows();
+}
+

backends/imgui_impl_dx10.h

@@ -2,7 +2,8 @@
 // This needs to be used along with a Platform Backend (e.g. Win32)
 
 // Implemented features:
-//  [X] Renderer: User texture backend. Use 'ID3D10ShaderResourceView*' as ImTextureID. Read the FAQ about ImTextureID!
+//  [X] Renderer: User texture binding. Use 'ID3D10ShaderResourceView*' as ImTextureID. Read the FAQ about ImTextureID!
+//  [X] Renderer: Multi-viewport support. Enable with 'io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable'.
 //  [X] Renderer: Support for large meshes (64k+ vertices) with 16-bit indices.
 
 // You can copy and use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.

backends/imgui_impl_dx11.cpp

@@ -3,6 +3,7 @@
 
 // Implemented features:
 //  [X] Renderer: User texture binding. Use 'ID3D11ShaderResourceView*' as ImTextureID. Read the FAQ about ImTextureID!
+//  [X] Renderer: Multi-viewport support. Enable with 'io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable'.
 //  [X] Renderer: Support for large meshes (64k+ vertices) with 16-bit indices.
 
 // You can copy and use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
@@ -11,6 +12,7 @@
 
 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
+//  2020-XX-XX: Platform: Added support for multiple windows via the ImGuiPlatformIO interface.
 //  2019-08-01: DirectX11: Fixed code querying the Geometry Shader state (would generally error with Debug layer enabled).
 //  2019-07-21: DirectX11: Backup, clear and restore Geometry Shader is any is bound when calling ImGui_ImplDX10_RenderDrawData. Clearing Hull/Domain/Compute shaders without backup/restore.
 //  2019-05-29: DirectX11: Added support for large mesh (64K+ vertices), enable ImGuiBackendFlags_RendererHasVtxOffset flag.
@@ -58,6 +60,10 @@ struct VERTEX_CONSTANT_BUFFER
     float   mvp[4][4];
 };
 
+// Forward Declarations
+static void ImGui_ImplDX11_InitPlatformInterface();
+static void ImGui_ImplDX11_ShutdownPlatformInterface();
+
 static void ImGui_ImplDX11_SetupRenderState(ImDrawData* draw_data, ID3D11DeviceContext* ctx)
 {
     // Setup viewport
@@ -513,6 +519,7 @@ bool    ImGui_ImplDX11_Init(ID3D11Device* device, ID3D11DeviceContext* device_co
     ImGuiIO& io = ImGui::GetIO();
     io.BackendRendererName = "imgui_impl_dx11";
     io.BackendFlags |= ImGuiBackendFlags_RendererHasVtxOffset;  // We can honor the ImDrawCmd::VtxOffset field, allowing for large meshes.
+    io.BackendFlags |= ImGuiBackendFlags_RendererHasViewports;  // We can create multi-viewports on the Renderer side (optional)
 
     // Get factory from device
     IDXGIDevice* pDXGIDevice = NULL;
@@ -532,11 +539,15 @@ bool    ImGui_ImplDX11_Init(ID3D11Device* device, ID3D11DeviceContext* device_co
     g_pd3dDevice->AddRef();
     g_pd3dDeviceContext->AddRef();
 
+    if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+        ImGui_ImplDX11_InitPlatformInterface();
+
     return true;
 }
 
 void ImGui_ImplDX11_Shutdown()
 {
+    ImGui_ImplDX11_ShutdownPlatformInterface();
     ImGui_ImplDX11_InvalidateDeviceObjects();
     if (g_pFactory) { g_pFactory->Release(); g_pFactory = NULL; }
     if (g_pd3dDevice) { g_pd3dDevice->Release(); g_pd3dDevice = NULL; }
@@ -548,3 +559,123 @@ void ImGui_ImplDX11_NewFrame()
     if (!g_pFontSampler)
         ImGui_ImplDX11_CreateDeviceObjects();
 }
+
+//--------------------------------------------------------------------------------------------------------
+// MULTI-VIEWPORT / PLATFORM INTERFACE SUPPORT
+// This is an _advanced_ and _optional_ feature, allowing the backend to create and handle multiple viewports simultaneously.
+// If you are new to dear imgui or creating a new binding for dear imgui, it is recommended that you completely ignore this section first..
+//--------------------------------------------------------------------------------------------------------
+
+// Helper structure we store in the void* RenderUserData field of each ImGuiViewport to easily retrieve our backend data.
+struct ImGuiViewportDataDx11
+{
+    IDXGISwapChain*             SwapChain;
+    ID3D11RenderTargetView*     RTView;
+
+    ImGuiViewportDataDx11()     { SwapChain = NULL; RTView = NULL; }
+    ~ImGuiViewportDataDx11()    { IM_ASSERT(SwapChain == NULL && RTView == NULL); }
+};
+
+static void ImGui_ImplDX11_CreateWindow(ImGuiViewport* viewport)
+{
+    ImGuiViewportDataDx11* data = IM_NEW(ImGuiViewportDataDx11)();
+    viewport->RendererUserData = data;
+
+    // PlatformHandleRaw should always be a HWND, whereas PlatformHandle might be a higher-level handle (e.g. GLFWWindow*, SDL_Window*).
+    // Some backend will leave PlatformHandleRaw NULL, in which case we assume PlatformHandle will contain the HWND.
+    HWND hwnd = viewport->PlatformHandleRaw ? (HWND)viewport->PlatformHandleRaw : (HWND)viewport->PlatformHandle;
+    IM_ASSERT(hwnd != 0);
+
+    // Create swap chain
+    DXGI_SWAP_CHAIN_DESC sd;
+    ZeroMemory(&sd, sizeof(sd));
+    sd.BufferDesc.Width = (UINT)viewport->Size.x;
+    sd.BufferDesc.Height = (UINT)viewport->Size.y;
+    sd.BufferDesc.Format = DXGI_FORMAT_R8G8B8A8_UNORM;
+    sd.SampleDesc.Count = 1;
+    sd.SampleDesc.Quality = 0;
+    sd.BufferUsage = DXGI_USAGE_RENDER_TARGET_OUTPUT;
+    sd.BufferCount = 1;
+    sd.OutputWindow = hwnd;
+    sd.Windowed = TRUE;
+    sd.SwapEffect = DXGI_SWAP_EFFECT_DISCARD;
+    sd.Flags = 0;
+
+    IM_ASSERT(data->SwapChain == NULL && data->RTView == NULL);
+    g_pFactory->CreateSwapChain(g_pd3dDevice, &sd, &data->SwapChain);
+
+    // Create the render target
+    if (data->SwapChain)
+    {
+        ID3D11Texture2D* pBackBuffer;
+        data->SwapChain->GetBuffer(0, IID_PPV_ARGS(&pBackBuffer));
+        g_pd3dDevice->CreateRenderTargetView(pBackBuffer, NULL, &data->RTView);
+        pBackBuffer->Release();
+    }
+}
+
+static void ImGui_ImplDX11_DestroyWindow(ImGuiViewport* viewport)
+{
+    // The main viewport (owned by the application) will always have RendererUserData == NULL since we didn't create the data for it.
+    if (ImGuiViewportDataDx11* data = (ImGuiViewportDataDx11*)viewport->RendererUserData)
+    {
+        if (data->SwapChain)
+            data->SwapChain->Release();
+        data->SwapChain = NULL;
+        if (data->RTView)
+            data->RTView->Release();
+        data->RTView = NULL;
+        IM_DELETE(data);
+    }
+    viewport->RendererUserData = NULL;
+}
+
+static void ImGui_ImplDX11_SetWindowSize(ImGuiViewport* viewport, ImVec2 size)
+{
+    ImGuiViewportDataDx11* data = (ImGuiViewportDataDx11*)viewport->RendererUserData;
+    if (data->RTView)
+    {
+        data->RTView->Release();
+        data->RTView = NULL;
+    }
+    if (data->SwapChain)
+    {
+        ID3D11Texture2D* pBackBuffer = NULL;
+        data->SwapChain->ResizeBuffers(0, (UINT)size.x, (UINT)size.y, DXGI_FORMAT_UNKNOWN, 0);
+        data->SwapChain->GetBuffer(0, IID_PPV_ARGS(&pBackBuffer));
+        if (pBackBuffer == NULL) { fprintf(stderr, "ImGui_ImplDX11_SetWindowSize() failed creating buffers.\n"); return; }
+        g_pd3dDevice->CreateRenderTargetView(pBackBuffer, NULL, &data->RTView);
+        pBackBuffer->Release();
+    }
+}
+
+static void ImGui_ImplDX11_RenderWindow(ImGuiViewport* viewport, void*)
+{
+    ImGuiViewportDataDx11* data = (ImGuiViewportDataDx11*)viewport->RendererUserData;
+    ImVec4 clear_color = ImVec4(0.0f, 0.0f, 0.0f, 1.0f);
+    g_pd3dDeviceContext->OMSetRenderTargets(1, &data->RTView, NULL);
+    if (!(viewport->Flags & ImGuiViewportFlags_NoRendererClear))
+        g_pd3dDeviceContext->ClearRenderTargetView(data->RTView, (float*)&clear_color);
+    ImGui_ImplDX11_RenderDrawData(viewport->DrawData);
+}
+
+static void ImGui_ImplDX11_SwapBuffers(ImGuiViewport* viewport, void*)
+{
+    ImGuiViewportDataDx11* data = (ImGuiViewportDataDx11*)viewport->RendererUserData;
+    data->SwapChain->Present(0, 0); // Present without vsync
+}
+
+static void ImGui_ImplDX11_InitPlatformInterface()
+{
+    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
+    platform_io.Renderer_CreateWindow = ImGui_ImplDX11_CreateWindow;
+    platform_io.Renderer_DestroyWindow = ImGui_ImplDX11_DestroyWindow;
+    platform_io.Renderer_SetWindowSize = ImGui_ImplDX11_SetWindowSize;
+    platform_io.Renderer_RenderWindow = ImGui_ImplDX11_RenderWindow;
+    platform_io.Renderer_SwapBuffers = ImGui_ImplDX11_SwapBuffers;
+}
+
+static void ImGui_ImplDX11_ShutdownPlatformInterface()
+{
+    ImGui::DestroyPlatformWindows();
+}

backends/imgui_impl_dx11.h

@@ -3,6 +3,7 @@
 
 // Implemented features:
 //  [X] Renderer: User texture binding. Use 'ID3D11ShaderResourceView*' as ImTextureID. Read the FAQ about ImTextureID!
+//  [X] Renderer: Multi-viewport support. Enable with 'io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable'.
 //  [X] Renderer: Support for large meshes (64k+ vertices) with 16-bit indices.
 
 // You can copy and use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.

backends/imgui_impl_dx12.cpp

@@ -3,11 +3,13 @@
 
 // Implemented features:
 //  [X] Renderer: User texture binding. Use 'D3D12_GPU_DESCRIPTOR_HANDLE' as ImTextureID. Read the FAQ about ImTextureID!
+//  [X] Renderer: Multi-viewport support. Enable with 'io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable'.
+//      FIXME: The transition from removing a viewport and moving the window in an existing hosted viewport tends to flicker.
 //  [X] Renderer: Support for large meshes (64k+ vertices) with 16-bit indices.
 
 // Important: to compile on 32-bit systems, this backend requires code to be compiled with '#define ImTextureID ImU64'.
 // This is because we need ImTextureID to carry a 64-bit value and by default ImTextureID is defined as void*.
-// This define is set in the example .vcxproj file and need to be replicated in your app or by adding it to your imconfig.h file.
+// This define is done in the example .vcxproj file and need to be replicated in your app (by e.g. editing imconfig.h)
 
 // You can copy and use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
 // If you are new to Dear ImGui, read documentation from the docs/ folder + read the top of imgui.cpp.
@@ -15,7 +17,7 @@
 
 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
-//  2021-01-11: DirectX12: Improve Windows 7 compatibility (for D3D12On7) by loading d3d12.dll dynamically.
+//  2020-XX-XX: Platform: Added support for multiple windows via the ImGuiPlatformIO interface.
 //  2020-09-16: DirectX12: Avoid rendering calls with zero-sized scissor rectangle since it generates a validation layer warning.
 //  2020-09-08: DirectX12: Clarified support for building on 32-bit systems by redefining ImTextureID.
 //  2019-10-18: DirectX12: *BREAKING CHANGE* Added extra ID3D12DescriptorHeap parameter to ImGui_ImplDX12_Init() function.
@@ -48,17 +50,88 @@ static DXGI_FORMAT                  g_RTVFormat = DXGI_FORMAT_UNKNOWN;
 static ID3D12Resource*              g_pFontTextureResource = NULL;
 static D3D12_CPU_DESCRIPTOR_HANDLE  g_hFontSrvCpuDescHandle = {};
 static D3D12_GPU_DESCRIPTOR_HANDLE  g_hFontSrvGpuDescHandle = {};
+static ID3D12DescriptorHeap*        g_pd3dSrvDescHeap = NULL;
+static UINT                         g_numFramesInFlight = 0;
 
-struct FrameResources
+// Buffers used during the rendering of a frame
+struct ImGui_ImplDX12_RenderBuffers
 {
     ID3D12Resource*     IndexBuffer;
     ID3D12Resource*     VertexBuffer;
     int                 IndexBufferSize;
     int                 VertexBufferSize;
 };
-static FrameResources*  g_pFrameResources = NULL;
-static UINT             g_numFramesInFlight = 0;
-static UINT             g_frameIndex = UINT_MAX;
+
+// Buffers used for secondary viewports created by the multi-viewports systems
+struct ImGui_ImplDX12_FrameContext
+{
+    ID3D12CommandAllocator*         CommandAllocator;
+    ID3D12Resource*                 RenderTarget;
+    D3D12_CPU_DESCRIPTOR_HANDLE     RenderTargetCpuDescriptors;
+};
+
+// Helper structure we store in the void* RendererUserData field of each ImGuiViewport to easily retrieve our backend data.
+// Main viewport created by application will only use the Resources field.
+// Secondary viewports created by this backend will use all the fields (including Window fields),
+struct ImGuiViewportDataDx12
+{
+    // Window
+    ID3D12CommandQueue*             CommandQueue;
+    ID3D12GraphicsCommandList*      CommandList;
+    ID3D12DescriptorHeap*           RtvDescHeap;
+    IDXGISwapChain3*                SwapChain;
+    ID3D12Fence*                    Fence;
+    UINT64                          FenceSignaledValue;
+    HANDLE                          FenceEvent;
+    ImGui_ImplDX12_FrameContext*    FrameCtx;
+
+    // Render buffers
+    UINT                            FrameIndex;
+    ImGui_ImplDX12_RenderBuffers*   FrameRenderBuffers;
+
+    ImGuiViewportDataDx12()
+    {
+        CommandQueue = NULL;
+        CommandList = NULL;
+        RtvDescHeap = NULL;
+        SwapChain = NULL;
+        Fence = NULL;
+        FenceSignaledValue = 0;
+        FenceEvent = NULL;
+        FrameCtx = new ImGui_ImplDX12_FrameContext[g_numFramesInFlight];
+        FrameIndex = UINT_MAX;
+        FrameRenderBuffers = new ImGui_ImplDX12_RenderBuffers[g_numFramesInFlight];
+
+        for (UINT i = 0; i < g_numFramesInFlight; ++i)
+        {
+            FrameCtx[i].CommandAllocator = NULL;
+            FrameCtx[i].RenderTarget = NULL;
+
+            // Create buffers with a default size (they will later be grown as needed)
+            FrameRenderBuffers[i].IndexBuffer = NULL;
+            FrameRenderBuffers[i].VertexBuffer = NULL;
+            FrameRenderBuffers[i].VertexBufferSize = 5000;
+            FrameRenderBuffers[i].IndexBufferSize = 10000;
+        }
+    }
+    ~ImGuiViewportDataDx12()
+    {
+        IM_ASSERT(CommandQueue == NULL && CommandList == NULL);
+        IM_ASSERT(RtvDescHeap == NULL);
+        IM_ASSERT(SwapChain == NULL);
+        IM_ASSERT(Fence == NULL);
+        IM_ASSERT(FenceEvent == NULL);
+
+        for (UINT i = 0; i < g_numFramesInFlight; ++i)
+        {
+            IM_ASSERT(FrameCtx[i].CommandAllocator == NULL && FrameCtx[i].RenderTarget == NULL);
+            IM_ASSERT(FrameRenderBuffers[i].IndexBuffer == NULL && FrameRenderBuffers[i].VertexBuffer == NULL);
+        }
+
+        delete[] FrameCtx; FrameCtx = NULL;
+        delete[] FrameRenderBuffers; FrameRenderBuffers = NULL;
+    }
+};
 
 template<typename T>
 static void SafeRelease(T*& res)
@@ -68,12 +141,23 @@ static void SafeRelease(T*& res)
     res = NULL;
 }
 
+static void ImGui_ImplDX12_DestroyRenderBuffers(ImGui_ImplDX12_RenderBuffers* render_buffers)
+{
+    SafeRelease(render_buffers->IndexBuffer);
+    SafeRelease(render_buffers->VertexBuffer);
+    render_buffers->IndexBufferSize = render_buffers->VertexBufferSize = 0;
+}
+
 struct VERTEX_CONSTANT_BUFFER
 {
     float   mvp[4][4];
 };
 
-static void ImGui_ImplDX12_SetupRenderState(ImDrawData* draw_data, ID3D12GraphicsCommandList* ctx, FrameResources* fr)
+// Forward Declarations
+static void ImGui_ImplDX12_InitPlatformInterface();
+static void ImGui_ImplDX12_ShutdownPlatformInterface();
+
+static void ImGui_ImplDX12_SetupRenderState(ImDrawData* draw_data, ID3D12GraphicsCommandList* ctx, ImGui_ImplDX12_RenderBuffers* fr)
 {
     // Setup orthographic projection matrix into our constant buffer
     // Our visible imgui space lies from draw_data->DisplayPos (top left) to draw_data->DisplayPos+data_data->DisplaySize (bottom right).
@@ -135,10 +219,9 @@ void ImGui_ImplDX12_RenderDrawData(ImDrawData* draw_data, ID3D12GraphicsCommandL
     if (draw_data->DisplaySize.x <= 0.0f || draw_data->DisplaySize.y <= 0.0f)
         return;
 
-    // FIXME: I'm assuming that this only gets called once per frame!
-    // If not, we can't just re-allocate the IB or VB, we'll have to do a proper allocator.
-    g_frameIndex = g_frameIndex + 1;
-    FrameResources* fr = &g_pFrameResources[g_frameIndex % g_numFramesInFlight];
+    ImGuiViewportDataDx12* render_data = (ImGuiViewportDataDx12*)draw_data->OwnerViewport->RendererUserData;
+    render_data->FrameIndex++;
+    ImGui_ImplDX12_RenderBuffers* fr = &render_data->FrameRenderBuffers[render_data->FrameIndex % g_numFramesInFlight];
 
     // Create and grow vertex/index buffers if needed
     if (fr->VertexBuffer == NULL || fr->VertexBufferSize < draw_data->TotalVtxCount)
@@ -453,34 +536,8 @@ bool    ImGui_ImplDX12_CreateDeviceObjects()
             D3D12_ROOT_SIGNATURE_FLAG_DENY_DOMAIN_SHADER_ROOT_ACCESS |
             D3D12_ROOT_SIGNATURE_FLAG_DENY_GEOMETRY_SHADER_ROOT_ACCESS;
 
-        // Load d3d12.dll and D3D12SerializeRootSignature() function address dynamically to facilitate using with D3D12On7.
-        // See if any version of d3d12.dll is already loaded in the process. If so, give preference to that.
-        static HINSTANCE d3d12_dll = ::GetModuleHandleA("d3d12.dll");
-        if (d3d12_dll == NULL)
-        {
-            // Attempt to load d3d12.dll from local directories. This will only succeed if
-            // (1) the current OS is Windows 7, and
-            // (2) there exists a version of d3d12.dll for Windows 7 (D3D12On7) in one of the following directories.
-            // See https://github.com/ocornut/imgui/pull/3696 for details.
-            const char* localD3d12Paths[] = { ".\\d3d12.dll", ".\\d3d12on7\\d3d12.dll", ".\\12on7\\d3d12.dll" }; // A. current directory, B. used by some games, C. used in Microsoft D3D12On7 sample
-            for (int i = 0; i < IM_ARRAYSIZE(localD3d12Paths); i++)
-                if ((d3d12_dll = ::LoadLibraryA(localD3d12Paths[i])) != NULL)
-                    break;
-
-            // If failed, we are on Windows >= 10.
-            if (d3d12_dll == NULL)
-                d3d12_dll = ::LoadLibraryA("d3d12.dll");
-
-            if (d3d12_dll == NULL)
-                return false;
-        }
-
-        PFN_D3D12_SERIALIZE_ROOT_SIGNATURE D3D12SerializeRootSignatureFn = (PFN_D3D12_SERIALIZE_ROOT_SIGNATURE)::GetProcAddress(d3d12_dll, "D3D12SerializeRootSignature");
-        if (D3D12SerializeRootSignatureFn == NULL)
-            return false;
-
         ID3DBlob* blob = NULL;
-        if (D3D12SerializeRootSignatureFn(&desc, D3D_ROOT_SIGNATURE_VERSION_1, &blob, NULL) != S_OK)
+        if (D3D12SerializeRootSignature(&desc, D3D_ROOT_SIGNATURE_VERSION_1, &blob, NULL) != S_OK)
             return false;
 
         g_pd3dDevice->CreateRootSignature(0, blob->GetBufferPointer(), blob->GetBufferSize(), IID_PPV_ARGS(&g_pRootSignature));
@@ -641,13 +698,6 @@ void    ImGui_ImplDX12_InvalidateDeviceObjects()
 
     ImGuiIO& io = ImGui::GetIO();
     io.Fonts->TexID = NULL; // We copied g_pFontTextureView to io.Fonts->TexID so let's clear that as well.
-
-    for (UINT i = 0; i < g_numFramesInFlight; i++)
-    {
-        FrameResources* fr = &g_pFrameResources[i];
-        SafeRelease(fr->IndexBuffer);
-        SafeRelease(fr->VertexBuffer);
-    }
 }
 
 bool ImGui_ImplDX12_Init(ID3D12Device* device, int num_frames_in_flight, DXGI_FORMAT rtv_format, ID3D12DescriptorHeap* cbv_srv_heap,
@@ -657,39 +707,50 @@ bool ImGui_ImplDX12_Init(ID3D12Device* device, int num_frames_in_flight, DXGI_FO
     ImGuiIO& io = ImGui::GetIO();
     io.BackendRendererName = "imgui_impl_dx12";
     io.BackendFlags |= ImGuiBackendFlags_RendererHasVtxOffset;  // We can honor the ImDrawCmd::VtxOffset field, allowing for large meshes.
+    io.BackendFlags |= ImGuiBackendFlags_RendererHasViewports;  // We can create multi-viewports on the Renderer side (optional) // FIXME-VIEWPORT: Actually unfinished..
 
     g_pd3dDevice = device;
     g_RTVFormat = rtv_format;
     g_hFontSrvCpuDescHandle = font_srv_cpu_desc_handle;
     g_hFontSrvGpuDescHandle = font_srv_gpu_desc_handle;
-    g_pFrameResources = new FrameResources[num_frames_in_flight];
     g_numFramesInFlight = num_frames_in_flight;
-    g_frameIndex = UINT_MAX;
-    IM_UNUSED(cbv_srv_heap); // Unused in master branch (will be used by multi-viewports)
+    g_pd3dSrvDescHeap = cbv_srv_heap;
 
-    // Create buffers with a default size (they will later be grown as needed)
-    for (int i = 0; i < num_frames_in_flight; i++)
-    {
-        FrameResources* fr = &g_pFrameResources[i];
-        fr->IndexBuffer = NULL;
-        fr->VertexBuffer = NULL;
-        fr->IndexBufferSize = 10000;
-        fr->VertexBufferSize = 5000;
-    }
+    // Create a dummy ImGuiViewportDataDx12 holder for the main viewport,
+    // Since this is created and managed by the application, we will only use the ->Resources[] fields.
+    ImGuiViewport* main_viewport = ImGui::GetMainViewport();
+    main_viewport->RendererUserData = IM_NEW(ImGuiViewportDataDx12)();
+
+    // Setup backend capabilities flags
+    io.BackendFlags |= ImGuiBackendFlags_RendererHasViewports;    // We can create multi-viewports on the Renderer side (optional)
+    if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+        ImGui_ImplDX12_InitPlatformInterface();
 
     return true;
 }
 
 void ImGui_ImplDX12_Shutdown()
 {
+    // Manually delete main viewport render resources in-case we haven't initialized for viewports
+    ImGuiViewport* main_viewport = ImGui::GetMainViewport();
+    if (ImGuiViewportDataDx12* data = (ImGuiViewportDataDx12*)main_viewport->RendererUserData)
+    {
+        // We could just call ImGui_ImplDX12_DestroyWindow(main_viewport) as a convenience but that would be misleading since we only use data->Resources[]
+        for (UINT i = 0; i < g_numFramesInFlight; i++)
+            ImGui_ImplDX12_DestroyRenderBuffers(&data->FrameRenderBuffers[i]);
+        IM_DELETE(data);
+        main_viewport->RendererUserData = NULL;
+    }
+
+    // Clean up windows and device objects
+    ImGui_ImplDX12_ShutdownPlatformInterface();
     ImGui_ImplDX12_InvalidateDeviceObjects();
-    delete[] g_pFrameResources;
-    g_pFrameResources = NULL;
+
     g_pd3dDevice = NULL;
     g_hFontSrvCpuDescHandle.ptr = 0;
     g_hFontSrvGpuDescHandle.ptr = 0;
     g_numFramesInFlight = 0;
-    g_frameIndex = UINT_MAX;
+    g_pd3dSrvDescHeap = NULL;
 }
 
 void ImGui_ImplDX12_NewFrame()
@@ -697,3 +758,239 @@ void ImGui_ImplDX12_NewFrame()
     if (!g_pPipelineState)
         ImGui_ImplDX12_CreateDeviceObjects();
 }
+
+//--------------------------------------------------------------------------------------------------------
+// MULTI-VIEWPORT / PLATFORM INTERFACE SUPPORT
+// This is an _advanced_ and _optional_ feature, allowing the backend to create and handle multiple viewports simultaneously.
+// If you are new to dear imgui or creating a new binding for dear imgui, it is recommended that you completely ignore this section first..
+//--------------------------------------------------------------------------------------------------------
+
+static void ImGui_ImplDX12_CreateWindow(ImGuiViewport* viewport)
+{
+    ImGuiViewportDataDx12* data = IM_NEW(ImGuiViewportDataDx12)();
+    viewport->RendererUserData = data;
+
+    // PlatformHandleRaw should always be a HWND, whereas PlatformHandle might be a higher-level handle (e.g. GLFWWindow*, SDL_Window*).
+    // Some backends will leave PlatformHandleRaw NULL, in which case we assume PlatformHandle will contain the HWND.
+    HWND hwnd = viewport->PlatformHandleRaw ? (HWND)viewport->PlatformHandleRaw : (HWND)viewport->PlatformHandle;
+    IM_ASSERT(hwnd != 0);
+
+    data->FrameIndex = UINT_MAX;
+
+    // Create command queue.
+    D3D12_COMMAND_QUEUE_DESC queue_desc = {};
+    queue_desc.Flags = D3D12_COMMAND_QUEUE_FLAG_NONE;
+    queue_desc.Type = D3D12_COMMAND_LIST_TYPE_DIRECT;
+
+    HRESULT res = S_OK;
+    res = g_pd3dDevice->CreateCommandQueue(&queue_desc, IID_PPV_ARGS(&data->CommandQueue));
+    IM_ASSERT(res == S_OK);
+
+    // Create command allocator.
+    for (UINT i = 0; i < g_numFramesInFlight; ++i)
+    {
+        res = g_pd3dDevice->CreateCommandAllocator(D3D12_COMMAND_LIST_TYPE_DIRECT, IID_PPV_ARGS(&data->FrameCtx[i].CommandAllocator));
+        IM_ASSERT(res == S_OK);
+    }
+
+    // Create command list.
+    res = g_pd3dDevice->CreateCommandList(0, D3D12_COMMAND_LIST_TYPE_DIRECT, data->FrameCtx[0].CommandAllocator, NULL, IID_PPV_ARGS(&data->CommandList));
+    IM_ASSERT(res == S_OK);
+    data->CommandList->Close();
+
+    // Create fence.
+    res = g_pd3dDevice->CreateFence(0, D3D12_FENCE_FLAG_NONE, IID_PPV_ARGS(&data->Fence));
+    IM_ASSERT(res == S_OK);
+
+    data->FenceEvent = CreateEvent(NULL, FALSE, FALSE, NULL);
+    IM_ASSERT(data->FenceEvent != NULL);
+
+    // Create swap chain
+    // FIXME-VIEWPORT: May want to copy/inherit swap chain settings from the user/application.
+    DXGI_SWAP_CHAIN_DESC1 sd1;
+    ZeroMemory(&sd1, sizeof(sd1));
+    sd1.BufferCount = g_numFramesInFlight;
+    sd1.Width = (UINT)viewport->Size.x;
+    sd1.Height = (UINT)viewport->Size.y;
+    sd1.Format = g_RTVFormat;
+    sd1.BufferUsage = DXGI_USAGE_RENDER_TARGET_OUTPUT;
+    sd1.SampleDesc.Count = 1;
+    sd1.SampleDesc.Quality = 0;
+    sd1.SwapEffect = DXGI_SWAP_EFFECT_FLIP_DISCARD;
+    sd1.AlphaMode = DXGI_ALPHA_MODE_UNSPECIFIED;
+    sd1.Scaling = DXGI_SCALING_STRETCH;
+    sd1.Stereo = FALSE;
+
+    IDXGIFactory4* dxgi_factory = NULL;
+    res = ::CreateDXGIFactory1(IID_PPV_ARGS(&dxgi_factory));
+    IM_ASSERT(res == S_OK);
+
+    IDXGISwapChain1* swap_chain = NULL;
+    res = dxgi_factory->CreateSwapChainForHwnd(data->CommandQueue, hwnd, &sd1, NULL, NULL, &swap_chain);
+    IM_ASSERT(res == S_OK);
+
+    dxgi_factory->Release();
+
+    // Or swapChain.As(&mSwapChain)
+    IM_ASSERT(data->SwapChain == NULL);
+    swap_chain->QueryInterface(IID_PPV_ARGS(&data->SwapChain));
+    swap_chain->Release();
+
+    // Create the render targets
+    if (data->SwapChain)
+    {
+        D3D12_DESCRIPTOR_HEAP_DESC desc = {};
+        desc.Type = D3D12_DESCRIPTOR_HEAP_TYPE_RTV;
+        desc.NumDescriptors = g_numFramesInFlight;
+        desc.Flags = D3D12_DESCRIPTOR_HEAP_FLAG_NONE;
+        desc.NodeMask = 1;
+
+        HRESULT hr = g_pd3dDevice->CreateDescriptorHeap(&desc, IID_PPV_ARGS(&data->RtvDescHeap));
+        IM_ASSERT(hr == S_OK);
+
+        SIZE_T rtv_descriptor_size = g_pd3dDevice->GetDescriptorHandleIncrementSize(D3D12_DESCRIPTOR_HEAP_TYPE_RTV);
+        D3D12_CPU_DESCRIPTOR_HANDLE rtv_handle = data->RtvDescHeap->GetCPUDescriptorHandleForHeapStart();
+        for (UINT i = 0; i < g_numFramesInFlight; i++)
+        {
+            data->FrameCtx[i].RenderTargetCpuDescriptors = rtv_handle;
+            rtv_handle.ptr += rtv_descriptor_size;
+        }
+
+        ID3D12Resource* back_buffer;
+        for (UINT i = 0; i < g_numFramesInFlight; i++)
+        {
+            IM_ASSERT(data->FrameCtx[i].RenderTarget == NULL);
+            data->SwapChain->GetBuffer(i, IID_PPV_ARGS(&back_buffer));
+            g_pd3dDevice->CreateRenderTargetView(back_buffer, NULL, data->FrameCtx[i].RenderTargetCpuDescriptors);
+            data->FrameCtx[i].RenderTarget = back_buffer;
+        }
+    }
+
+    for (UINT i = 0; i < g_numFramesInFlight; i++)
+        ImGui_ImplDX12_DestroyRenderBuffers(&data->FrameRenderBuffers[i]);
+}
+
+static void ImGui_WaitForPendingOperations(ImGuiViewportDataDx12* data)
+{
+    HRESULT hr = S_FALSE;
+    if (data && data->CommandQueue && data->Fence && data->FenceEvent)
+    {
+        hr = data->CommandQueue->Signal(data->Fence, ++data->FenceSignaledValue);
+        IM_ASSERT(hr == S_OK);
+        ::WaitForSingleObject(data->FenceEvent, 0); // Reset any forgotten waits
+        hr = data->Fence->SetEventOnCompletion(data->FenceSignaledValue, data->FenceEvent);
+        IM_ASSERT(hr == S_OK);
+        ::WaitForSingleObject(data->FenceEvent, INFINITE);
+    }
+}
+
+static void ImGui_ImplDX12_DestroyWindow(ImGuiViewport* viewport)
+{
+    // The main viewport (owned by the application) will always have RendererUserData == NULL since we didn't create the data for it.
+    if (ImGuiViewportDataDx12* data = (ImGuiViewportDataDx12*)viewport->RendererUserData)
+    {
+        ImGui_WaitForPendingOperations(data);
+
+        SafeRelease(data->CommandQueue);
+        SafeRelease(data->CommandList);
+        SafeRelease(data->SwapChain);
+        SafeRelease(data->RtvDescHeap);
+        SafeRelease(data->Fence);
+        ::CloseHandle(data->FenceEvent);
+        data->FenceEvent = NULL;
+
+        for (UINT i = 0; i < g_numFramesInFlight; i++)
+        {
+            SafeRelease(data->FrameCtx[i].RenderTarget);
+            SafeRelease(data->FrameCtx[i].CommandAllocator);
+            ImGui_ImplDX12_DestroyRenderBuffers(&data->FrameRenderBuffers[i]);
+        }
+        IM_DELETE(data);
+    }
+    viewport->RendererUserData = NULL;
+}
+
+static void ImGui_ImplDX12_SetWindowSize(ImGuiViewport* viewport, ImVec2 size)
+{
+    ImGuiViewportDataDx12* data = (ImGuiViewportDataDx12*)viewport->RendererUserData;
+
+    ImGui_WaitForPendingOperations(data);
+
+    for (UINT i = 0; i < g_numFramesInFlight; i++)
+        SafeRelease(data->FrameCtx[i].RenderTarget);
+
+    if (data->SwapChain)
+    {
+        ID3D12Resource* back_buffer = NULL;
+        data->SwapChain->ResizeBuffers(0, (UINT)size.x, (UINT)size.y, DXGI_FORMAT_UNKNOWN, 0);
+        for (UINT i = 0; i < g_numFramesInFlight; i++)
+        {
+            data->SwapChain->GetBuffer(i, IID_PPV_ARGS(&back_buffer));
+            g_pd3dDevice->CreateRenderTargetView(back_buffer, NULL, data->FrameCtx[i].RenderTargetCpuDescriptors);
+            data->FrameCtx[i].RenderTarget = back_buffer;
+        }
+    }
+}
+
+static void ImGui_ImplDX12_RenderWindow(ImGuiViewport* viewport, void*)
+{
+    ImGuiViewportDataDx12* data = (ImGuiViewportDataDx12*)viewport->RendererUserData;
+
+    ImGui_ImplDX12_FrameContext* frame_context = &data->FrameCtx[data->FrameIndex % g_numFramesInFlight];
+    UINT back_buffer_idx = data->SwapChain->GetCurrentBackBufferIndex();
+
+    const ImVec4 clear_color = ImVec4(0.0f, 0.0f, 0.0f, 1.0f);
+    D3D12_RESOURCE_BARRIER barrier = {};
+    barrier.Type = D3D12_RESOURCE_BARRIER_TYPE_TRANSITION;
+    barrier.Flags = D3D12_RESOURCE_BARRIER_FLAG_NONE;
+    barrier.Transition.pResource = data->FrameCtx[back_buffer_idx].RenderTarget;
+    barrier.Transition.Subresource = D3D12_RESOURCE_BARRIER_ALL_SUBRESOURCES;
+    barrier.Transition.StateBefore = D3D12_RESOURCE_STATE_PRESENT;
+    barrier.Transition.StateAfter = D3D12_RESOURCE_STATE_RENDER_TARGET;
+
+    // Draw
+    ID3D12GraphicsCommandList* cmd_list = data->CommandList;
+
+    frame_context->CommandAllocator->Reset();
+    cmd_list->Reset(frame_context->CommandAllocator, NULL);
+    cmd_list->ResourceBarrier(1, &barrier);
+    cmd_list->OMSetRenderTargets(1, &data->FrameCtx[back_buffer_idx].RenderTargetCpuDescriptors, FALSE, NULL);
+    if (!(viewport->Flags & ImGuiViewportFlags_NoRendererClear))
+        cmd_list->ClearRenderTargetView(data->FrameCtx[back_buffer_idx].RenderTargetCpuDescriptors, (float*)&clear_color, 0, NULL);
+    cmd_list->SetDescriptorHeaps(1, &g_pd3dSrvDescHeap);
+
+    ImGui_ImplDX12_RenderDrawData(viewport->DrawData, cmd_list);
+
+    barrier.Transition.StateBefore = D3D12_RESOURCE_STATE_RENDER_TARGET;
+    barrier.Transition.StateAfter = D3D12_RESOURCE_STATE_PRESENT;
+    cmd_list->ResourceBarrier(1, &barrier);
+    cmd_list->Close();
+
+    data->CommandQueue->Wait(data->Fence, data->FenceSignaledValue);
+    data->CommandQueue->ExecuteCommandLists(1, (ID3D12CommandList* const*)&cmd_list);
+    data->CommandQueue->Signal(data->Fence, ++data->FenceSignaledValue);
+}
+
+static void ImGui_ImplDX12_SwapBuffers(ImGuiViewport* viewport, void*)
+{
+    ImGuiViewportDataDx12* data = (ImGuiViewportDataDx12*)viewport->RendererUserData;
+
+    data->SwapChain->Present(0, 0);
+    while (data->Fence->GetCompletedValue() < data->FenceSignaledValue)
+        ::SwitchToThread();
+}
+
+void ImGui_ImplDX12_InitPlatformInterface()
+{
+    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
+    platform_io.Renderer_CreateWindow = ImGui_ImplDX12_CreateWindow;
+    platform_io.Renderer_DestroyWindow = ImGui_ImplDX12_DestroyWindow;
+    platform_io.Renderer_SetWindowSize = ImGui_ImplDX12_SetWindowSize;
+    platform_io.Renderer_RenderWindow = ImGui_ImplDX12_RenderWindow;
+    platform_io.Renderer_SwapBuffers = ImGui_ImplDX12_SwapBuffers;
+}
+
+void ImGui_ImplDX12_ShutdownPlatformInterface()
+{
+    ImGui::DestroyPlatformWindows();
+}

backends/imgui_impl_dx12.h

@@ -3,11 +3,12 @@
 
 // Implemented features:
 //  [X] Renderer: User texture binding. Use 'D3D12_GPU_DESCRIPTOR_HANDLE' as ImTextureID. Read the FAQ about ImTextureID!
+//  [X] Renderer: Multi-viewport support. Enable with 'io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable'.
 //  [X] Renderer: Support for large meshes (64k+ vertices) with 16-bit indices.
 
 // Important: to compile on 32-bit systems, this backend requires code to be compiled with '#define ImTextureID ImU64'.
 // This is because we need ImTextureID to carry a 64-bit value and by default ImTextureID is defined as void*.
-// This define is set in the example .vcxproj file and need to be replicated in your app or by adding it to your imconfig.h file.
+// This define is done in the example .vcxproj file and need to be replicated in your app (by e.g. editing imconfig.h)
 
 // You can copy and use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
 // If you are new to Dear ImGui, read documentation from the docs/ folder + read the top of imgui.cpp.
@@ -16,11 +17,6 @@
 #pragma once
 #include "imgui.h"      // IMGUI_IMPL_API
 
-#ifdef _MSC_VER
-#pragma warning (push)
-#pragma warning (disable: 4471) // a forward declaration of an unscoped enumeration must have an underlying type
-#endif
-
 enum DXGI_FORMAT;
 struct ID3D12Device;
 struct ID3D12DescriptorHeap;
@@ -41,8 +37,3 @@ IMGUI_IMPL_API void     ImGui_ImplDX12_RenderDrawData(ImDrawData* draw_data, ID3
 // Use if you want to reset your rendering device without losing Dear ImGui state.
 IMGUI_IMPL_API void     ImGui_ImplDX12_InvalidateDeviceObjects();
 IMGUI_IMPL_API bool     ImGui_ImplDX12_CreateDeviceObjects();
-
-#ifdef _MSC_VER
-#pragma warning (pop)
-#endif
-

backends/imgui_impl_dx9.cpp

@@ -3,6 +3,7 @@
 
 // Implemented features:
 //  [X] Renderer: User texture binding. Use 'LPDIRECT3DTEXTURE9' as ImTextureID. Read the FAQ about ImTextureID!
+//  [X] Renderer: Multi-viewport support. Enable with 'io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable'.
 //  [X] Renderer: Support for large meshes (64k+ vertices) with 16-bit indices.
 
 // You can copy and use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
@@ -11,6 +12,7 @@
 
 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
+//  2020-XX-XX: Platform: Added support for multiple windows via the ImGuiPlatformIO interface.
 //  2019-05-29: DirectX9: Added support for large mesh (64K+ vertices), enable ImGuiBackendFlags_RendererHasVtxOffset flag.
 //  2019-04-30: DirectX9: Added support for special ImDrawCallback_ResetRenderState callback to reset render state.
 //  2019-03-29: Misc: Fixed erroneous assert in ImGui_ImplDX9_InvalidateDeviceObjects().
@@ -45,6 +47,12 @@ struct CUSTOMVERTEX
 };
 #define D3DFVF_CUSTOMVERTEX (D3DFVF_XYZ|D3DFVF_DIFFUSE|D3DFVF_TEX1)
 
+// Forward Declarations
+static void ImGui_ImplDX9_InitPlatformInterface();
+static void ImGui_ImplDX9_ShutdownPlatformInterface();
+static void ImGui_ImplDX9_CreateDeviceObjectsForPlatformWindows();
+static void ImGui_ImplDX9_InvalidateDeviceObjectsForPlatformWindows();
+
 static void ImGui_ImplDX9_SetupRenderState(ImDrawData* draw_data)
 {
     // Setup viewport
@@ -205,6 +213,11 @@ void ImGui_ImplDX9_RenderDrawData(ImDrawData* draw_data)
         global_vtx_offset += cmd_list->VtxBuffer.Size;
     }
 
+    // When using multi-viewports, it appears that there's an odd logic in DirectX9 which prevent subsequent windows
+    // from rendering until the first window submits at least one draw call, even once. That's our workaround. (see #2560)
+    if (global_vtx_offset == 0)
+        g_pd3dDevice->DrawIndexedPrimitive(D3DPT_TRIANGLELIST, 0, 0, 0, 0, 0);
+
     // Restore the DX9 transform
     g_pd3dDevice->SetTransform(D3DTS_WORLD, &last_world);
     g_pd3dDevice->SetTransform(D3DTS_VIEW, &last_view);
@@ -221,14 +234,20 @@ bool ImGui_ImplDX9_Init(IDirect3DDevice9* device)
     ImGuiIO& io = ImGui::GetIO();
     io.BackendRendererName = "imgui_impl_dx9";
     io.BackendFlags |= ImGuiBackendFlags_RendererHasVtxOffset;  // We can honor the ImDrawCmd::VtxOffset field, allowing for large meshes.
+    io.BackendFlags |= ImGuiBackendFlags_RendererHasViewports;  // We can create multi-viewports on the Renderer side (optional)
 
     g_pd3dDevice = device;
     g_pd3dDevice->AddRef();
+
+    if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+        ImGui_ImplDX9_InitPlatformInterface();
+
     return true;
 }
 
 void ImGui_ImplDX9_Shutdown()
 {
+    ImGui_ImplDX9_ShutdownPlatformInterface();
     ImGui_ImplDX9_InvalidateDeviceObjects();
     if (g_pd3dDevice) { g_pd3dDevice->Release(); g_pd3dDevice = NULL; }
 }
@@ -264,6 +283,7 @@ bool ImGui_ImplDX9_CreateDeviceObjects()
         return false;
     if (!ImGui_ImplDX9_CreateFontsTexture())
         return false;
+    ImGui_ImplDX9_CreateDeviceObjectsForPlatformWindows();
     return true;
 }
 
@@ -274,6 +294,7 @@ void ImGui_ImplDX9_InvalidateDeviceObjects()
     if (g_pVB) { g_pVB->Release(); g_pVB = NULL; }
     if (g_pIB) { g_pIB->Release(); g_pIB = NULL; }
     if (g_FontTexture) { g_FontTexture->Release(); g_FontTexture = NULL; ImGui::GetIO().Fonts->TexID = NULL; } // We copied g_pFontTextureView to io.Fonts->TexID so let's clear that as well.
+    ImGui_ImplDX9_InvalidateDeviceObjectsForPlatformWindows();
 }
 
 void ImGui_ImplDX9_NewFrame()
@@ -281,3 +302,142 @@ void ImGui_ImplDX9_NewFrame()
     if (!g_FontTexture)
         ImGui_ImplDX9_CreateDeviceObjects();
 }
+
+//--------------------------------------------------------------------------------------------------------
+// MULTI-VIEWPORT / PLATFORM INTERFACE SUPPORT
+// This is an _advanced_ and _optional_ feature, allowing the backend to create and handle multiple viewports simultaneously.
+// If you are new to dear imgui or creating a new binding for dear imgui, it is recommended that you completely ignore this section first..
+//--------------------------------------------------------------------------------------------------------
+
+// Helper structure we store in the void* RenderUserData field of each ImGuiViewport to easily retrieve our backend data.
+struct ImGuiViewportDataDx9
+{
+    IDirect3DSwapChain9*    SwapChain;
+    D3DPRESENT_PARAMETERS   d3dpp;
+
+    ImGuiViewportDataDx9()  { SwapChain = NULL; ZeroMemory(&d3dpp, sizeof(D3DPRESENT_PARAMETERS)); }
+    ~ImGuiViewportDataDx9() { IM_ASSERT(SwapChain == NULL); }
+};
+
+static void ImGui_ImplDX9_CreateWindow(ImGuiViewport* viewport)
+{
+    ImGuiViewportDataDx9* data = IM_NEW(ImGuiViewportDataDx9)();
+    viewport->RendererUserData = data;
+
+    // PlatformHandleRaw should always be a HWND, whereas PlatformHandle might be a higher-level handle (e.g. GLFWWindow*, SDL_Window*).
+    // Some backends will leave PlatformHandleRaw NULL, in which case we assume PlatformHandle will contain the HWND.
+    HWND hwnd = viewport->PlatformHandleRaw ? (HWND)viewport->PlatformHandleRaw : (HWND)viewport->PlatformHandle;
+    IM_ASSERT(hwnd != 0);
+
+    ZeroMemory(&data->d3dpp, sizeof(D3DPRESENT_PARAMETERS));
+    data->d3dpp.Windowed = TRUE;
+    data->d3dpp.SwapEffect = D3DSWAPEFFECT_DISCARD;
+    data->d3dpp.BackBufferWidth = (UINT)viewport->Size.x;
+    data->d3dpp.BackBufferHeight = (UINT)viewport->Size.y;
+    data->d3dpp.BackBufferFormat = D3DFMT_UNKNOWN;
+    data->d3dpp.hDeviceWindow = hwnd;
+    data->d3dpp.EnableAutoDepthStencil = FALSE;
+    data->d3dpp.AutoDepthStencilFormat = D3DFMT_D16;
+    data->d3dpp.PresentationInterval = D3DPRESENT_INTERVAL_IMMEDIATE;   // Present without vsync
+    
+    HRESULT hr = g_pd3dDevice->CreateAdditionalSwapChain(&data->d3dpp, &data->SwapChain); IM_UNUSED(hr);
+    IM_ASSERT(hr == D3D_OK);
+    IM_ASSERT(data->SwapChain != NULL);
+}
+
+static void ImGui_ImplDX9_DestroyWindow(ImGuiViewport* viewport)
+{
+    // The main viewport (owned by the application) will always have RendererUserData == NULL since we didn't create the data for it.
+    if (ImGuiViewportDataDx9* data = (ImGuiViewportDataDx9*)viewport->RendererUserData)
+    {
+        if (data->SwapChain)
+            data->SwapChain->Release();
+        data->SwapChain = NULL;
+        ZeroMemory(&data->d3dpp, sizeof(D3DPRESENT_PARAMETERS));
+        IM_DELETE(data);
+    }
+    viewport->RendererUserData = NULL;
+}
+
+static void ImGui_ImplDX9_SetWindowSize(ImGuiViewport* viewport, ImVec2 size)
+{
+    ImGuiViewportDataDx9* data = (ImGuiViewportDataDx9*)viewport->RendererUserData;
+    if (data->SwapChain)
+    {
+        data->SwapChain->Release();
+        data->SwapChain = NULL;
+        data->d3dpp.BackBufferWidth = (UINT)size.x;
+        data->d3dpp.BackBufferHeight = (UINT)size.y;
+        HRESULT hr = g_pd3dDevice->CreateAdditionalSwapChain(&data->d3dpp, &data->SwapChain); IM_UNUSED(hr);
+        IM_ASSERT(hr == D3D_OK);
+    }
+}
+
+static void ImGui_ImplDX9_RenderWindow(ImGuiViewport* viewport, void*)
+{
+    ImGuiViewportDataDx9* data = (ImGuiViewportDataDx9*)viewport->RendererUserData;
+    ImVec4 clear_color = ImVec4(0.0f, 0.0f, 0.0f, 1.0f);
+
+    LPDIRECT3DSURFACE9 render_target = NULL;
+    LPDIRECT3DSURFACE9 last_render_target = NULL;
+    LPDIRECT3DSURFACE9 last_depth_stencil = NULL;
+    data->SwapChain->GetBackBuffer(0, D3DBACKBUFFER_TYPE_MONO, &render_target);
+    g_pd3dDevice->GetRenderTarget(0, &last_render_target);
+    g_pd3dDevice->GetDepthStencilSurface(&last_depth_stencil);
+    g_pd3dDevice->SetRenderTarget(0, render_target);
+    g_pd3dDevice->SetDepthStencilSurface(NULL);
+
+    if (!(viewport->Flags & ImGuiViewportFlags_NoRendererClear))
+    {
+        D3DCOLOR clear_col_dx = D3DCOLOR_RGBA((int)(clear_color.x*255.0f), (int)(clear_color.y*255.0f), (int)(clear_color.z*255.0f), (int)(clear_color.w*255.0f));
+        g_pd3dDevice->Clear(0, NULL, D3DCLEAR_TARGET, clear_col_dx, 1.0f, 0);
+    }
+
+    ImGui_ImplDX9_RenderDrawData(viewport->DrawData);
+
+    // Restore render target
+    g_pd3dDevice->SetRenderTarget(0, last_render_target);
+    g_pd3dDevice->SetDepthStencilSurface(last_depth_stencil);
+    render_target->Release();
+    last_render_target->Release();
+    if (last_depth_stencil) last_depth_stencil->Release();
+}
+
+static void ImGui_ImplDX9_SwapBuffers(ImGuiViewport* viewport, void*)
+{
+    ImGuiViewportDataDx9* data = (ImGuiViewportDataDx9*)viewport->RendererUserData;
+    HRESULT hr = data->SwapChain->Present(NULL, NULL, data->d3dpp.hDeviceWindow, NULL, NULL);
+    // Let main application handle D3DERR_DEVICELOST by resetting the device.
+    IM_ASSERT(hr == D3D_OK || hr == D3DERR_DEVICELOST);
+}
+
+static void ImGui_ImplDX9_InitPlatformInterface()
+{
+    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
+    platform_io.Renderer_CreateWindow = ImGui_ImplDX9_CreateWindow;
+    platform_io.Renderer_DestroyWindow = ImGui_ImplDX9_DestroyWindow;
+    platform_io.Renderer_SetWindowSize = ImGui_ImplDX9_SetWindowSize;
+    platform_io.Renderer_RenderWindow = ImGui_ImplDX9_RenderWindow;
+    platform_io.Renderer_SwapBuffers = ImGui_ImplDX9_SwapBuffers;
+}
+
+static void ImGui_ImplDX9_ShutdownPlatformInterface()
+{
+    ImGui::DestroyPlatformWindows();
+}
+
+static void ImGui_ImplDX9_CreateDeviceObjectsForPlatformWindows()
+{
+    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
+    for (int i = 1; i < platform_io.Viewports.Size; i++)
+        if (!platform_io.Viewports[i]->RendererUserData)
+            ImGui_ImplDX9_CreateWindow(platform_io.Viewports[i]);
+}
+
+static void ImGui_ImplDX9_InvalidateDeviceObjectsForPlatformWindows()
+{
+    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
+    for (int i = 1; i < platform_io.Viewports.Size; i++)
+        if (platform_io.Viewports[i]->RendererUserData)
+            ImGui_ImplDX9_DestroyWindow(platform_io.Viewports[i]);
+}

backends/imgui_impl_dx9.h

@@ -3,6 +3,7 @@
 
 // Implemented features:
 //  [X] Renderer: User texture binding. Use 'LPDIRECT3DTEXTURE9' as ImTextureID. Read the FAQ about ImTextureID!
+//  [X] Renderer: Multi-viewport support. Enable with 'io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable'.
 //  [X] Renderer: Support for large meshes (64k+ vertices) with 16-bit indices.
 
 // You can copy and use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.

backends/imgui_impl_glfw.cpp

@@ -1,13 +1,17 @@
 // dear imgui: Platform Backend for GLFW
 // This needs to be used along with a Renderer (e.g. OpenGL3, Vulkan..)
 // (Info: GLFW is a cross-platform general purpose library for handling windows, inputs, OpenGL/Vulkan graphics context creation, etc.)
-// (Requires: GLFW 3.1+)
+// (Requires: GLFW 3.1+. Prefer GLFW 3.3+ for full feature support.)
 
 // Implemented features:
 //  [X] Platform: Clipboard support.
 //  [X] Platform: Gamepad support. Enable with 'io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad'.
 //  [X] Platform: Mouse cursor shape and visibility. Disable with 'io.ConfigFlags |= ImGuiConfigFlags_NoMouseCursorChange' (note: the resizing cursors requires GLFW 3.4+).
 //  [X] Platform: Keyboard arrays indexed using GLFW_KEY_* codes, e.g. ImGui::IsKeyPressed(GLFW_KEY_SPACE).
+//  [X] Platform: Multi-viewport support (multiple windows). Enable with 'io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable'.
+
+// Issues:
+//  [ ] Platform: Multi-viewport support: ParentViewportID not honored, and so io.ConfigViewportsNoDefaultParent has no effect (minor).
 
 // You can copy and use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
 // If you are new to Dear ImGui, read documentation from the docs/ folder + read the top of imgui.cpp.
@@ -15,6 +19,7 @@
 
 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
+//  2020-XX-XX: Platform: Added support for multiple windows via the ImGuiPlatformIO interface.
 //  2020-01-17: Inputs: Disable error callback while assigning mouse cursors because some X11 setup don't have them and it generates errors.
 //  2019-12-05: Inputs: Added support for new mouse cursors added in GLFW 3.4+ (resizing cursors, not allowed cursor).
 //  2019-10-18: Misc: Previously installed user callbacks are now restored on shutdown.
@@ -52,11 +57,20 @@
 #define GLFW_HAS_WINDOW_ALPHA         (GLFW_VERSION_MAJOR * 1000 + GLFW_VERSION_MINOR * 100 >= 3300) // 3.3+ glfwSetWindowOpacity
 #define GLFW_HAS_PER_MONITOR_DPI      (GLFW_VERSION_MAJOR * 1000 + GLFW_VERSION_MINOR * 100 >= 3300) // 3.3+ glfwGetMonitorContentScale
 #define GLFW_HAS_VULKAN               (GLFW_VERSION_MAJOR * 1000 + GLFW_VERSION_MINOR * 100 >= 3200) // 3.2+ glfwCreateWindowSurface
-#ifdef GLFW_RESIZE_NESW_CURSOR  // let's be nice to people who pulled GLFW between 2019-04-16 (3.4 define) and 2019-11-29 (cursors defines) // FIXME: Remove when GLFW 3.4 is released?
+#define GLFW_HAS_FOCUS_WINDOW         (GLFW_VERSION_MAJOR * 1000 + GLFW_VERSION_MINOR * 100 >= 3200) // 3.2+ glfwFocusWindow
+#define GLFW_HAS_FOCUS_ON_SHOW        (GLFW_VERSION_MAJOR * 1000 + GLFW_VERSION_MINOR * 100 >= 3300) // 3.3+ GLFW_FOCUS_ON_SHOW
+#define GLFW_HAS_MONITOR_WORK_AREA    (GLFW_VERSION_MAJOR * 1000 + GLFW_VERSION_MINOR * 100 >= 3300) // 3.3+ glfwGetMonitorWorkarea
+#define GLFW_HAS_OSX_WINDOW_POS_FIX   (GLFW_VERSION_MAJOR * 1000 + GLFW_VERSION_MINOR * 100 + GLFW_VERSION_REVISION * 10 >= 3310) // 3.3.1+ Fixed: Resizing window repositions it on MacOS #1553
+#ifdef GLFW_RESIZE_NESW_CURSOR        // Let's be nice to people who pulled GLFW between 2019-04-16 (3.4 define) and 2019-11-29 (cursors defines) // FIXME: Remove when GLFW 3.4 is released?
 #define GLFW_HAS_NEW_CURSORS          (GLFW_VERSION_MAJOR * 1000 + GLFW_VERSION_MINOR * 100 >= 3400) // 3.4+ GLFW_RESIZE_ALL_CURSOR, GLFW_RESIZE_NESW_CURSOR, GLFW_RESIZE_NWSE_CURSOR, GLFW_NOT_ALLOWED_CURSOR
 #else
 #define GLFW_HAS_NEW_CURSORS          (0)
 #endif
+#ifdef GLFW_MOUSE_PASSTHROUGH         // Let's be nice to people who pulled GLFW between 2019-04-16 (3.4 define) and 2020-07-17 (passthrough)
+#define GLFW_HAS_MOUSE_PASSTHROUGH    (GLFW_VERSION_MAJOR * 1000 + GLFW_VERSION_MINOR * 100 >= 3400) // 3.4+ GLFW_MOUSE_PASSTHROUGH
+#else
+#define GLFW_HAS_MOUSE_PASSTHROUGH    (0)
+#endif
 
 // Data
 enum GlfwClientApi
@@ -71,12 +85,19 @@ static double               g_Time = 0.0;
 static bool                 g_MouseJustPressed[ImGuiMouseButton_COUNT] = {};
 static GLFWcursor*          g_MouseCursors[ImGuiMouseCursor_COUNT] = {};
 static bool                 g_InstalledCallbacks = false;
+static bool                 g_WantUpdateMonitors = true;
 
-// Chain GLFW callbacks: our callbacks will call the user's previously installed callbacks, if any.
+// Chain GLFW callbacks for main viewport: our callbacks will call the user's previously installed callbacks, if any.
 static GLFWmousebuttonfun   g_PrevUserCallbackMousebutton = NULL;
 static GLFWscrollfun        g_PrevUserCallbackScroll = NULL;
 static GLFWkeyfun           g_PrevUserCallbackKey = NULL;
 static GLFWcharfun          g_PrevUserCallbackChar = NULL;
+static GLFWmonitorfun       g_PrevUserCallbackMonitor = NULL;
+
+// Forward Declarations
+static void ImGui_ImplGlfw_UpdateMonitors();
+static void ImGui_ImplGlfw_InitPlatformInterface();
+static void ImGui_ImplGlfw_ShutdownPlatformInterface();
 
 static const char* ImGui_ImplGlfw_GetClipboardText(void* user_data)
 {
@@ -90,7 +111,7 @@ static void ImGui_ImplGlfw_SetClipboardText(void* user_data, const char* text)
 
 void ImGui_ImplGlfw_MouseButtonCallback(GLFWwindow* window, int button, int action, int mods)
 {
-    if (g_PrevUserCallbackMousebutton != NULL)
+    if (g_PrevUserCallbackMousebutton != NULL && window == g_Window)
         g_PrevUserCallbackMousebutton(window, button, action, mods);
 
     if (action == GLFW_PRESS && button >= 0 && button < IM_ARRAYSIZE(g_MouseJustPressed))
@@ -99,7 +120,7 @@ void ImGui_ImplGlfw_MouseButtonCallback(GLFWwindow* window, int button, int acti
 
 void ImGui_ImplGlfw_ScrollCallback(GLFWwindow* window, double xoffset, double yoffset)
 {
-    if (g_PrevUserCallbackScroll != NULL)
+    if (g_PrevUserCallbackScroll != NULL && window == g_Window)
         g_PrevUserCallbackScroll(window, xoffset, yoffset);
 
     ImGuiIO& io = ImGui::GetIO();
@@ -109,7 +130,7 @@ void ImGui_ImplGlfw_ScrollCallback(GLFWwindow* window, double xoffset, double yo
 
 void ImGui_ImplGlfw_KeyCallback(GLFWwindow* window, int key, int scancode, int action, int mods)
 {
-    if (g_PrevUserCallbackKey != NULL)
+    if (g_PrevUserCallbackKey != NULL && window == g_Window)
         g_PrevUserCallbackKey(window, key, scancode, action, mods);
 
     ImGuiIO& io = ImGui::GetIO();
@@ -131,13 +152,18 @@ void ImGui_ImplGlfw_KeyCallback(GLFWwindow* window, int key, int scancode, int a
 
 void ImGui_ImplGlfw_CharCallback(GLFWwindow* window, unsigned int c)
 {
-    if (g_PrevUserCallbackChar != NULL)
+    if (g_PrevUserCallbackChar != NULL && window == g_Window)
         g_PrevUserCallbackChar(window, c);
 
     ImGuiIO& io = ImGui::GetIO();
     io.AddInputCharacter(c);
 }
 
+void ImGui_ImplGlfw_MonitorCallback(GLFWmonitor*, int)
+{
+    g_WantUpdateMonitors = true;
+}
+
 static bool ImGui_ImplGlfw_Init(GLFWwindow* window, bool install_callbacks, GlfwClientApi client_api)
 {
     g_Window = window;
@@ -147,6 +173,10 @@ static bool ImGui_ImplGlfw_Init(GLFWwindow* window, bool install_callbacks, Glfw
     ImGuiIO& io = ImGui::GetIO();
     io.BackendFlags |= ImGuiBackendFlags_HasMouseCursors;         // We can honor GetMouseCursor() values (optional)
     io.BackendFlags |= ImGuiBackendFlags_HasSetMousePos;          // We can honor io.WantSetMousePos requests (optional, rarely used)
+    io.BackendFlags |= ImGuiBackendFlags_PlatformHasViewports;    // We can create multi-viewports on the Platform side (optional)
+#if GLFW_HAS_MOUSE_PASSTHROUGH || (GLFW_HAS_WINDOW_HOVERED && defined(_WIN32))
+    io.BackendFlags |= ImGuiBackendFlags_HasMouseHoveredViewport; // We can set io.MouseHoveredViewport correctly (optional, not easy)
+#endif
     io.BackendPlatformName = "imgui_impl_glfw";
 
     // Keyboard mapping. ImGui will use those indices to peek into the io.KeysDown[] array.
@@ -176,9 +206,6 @@ static bool ImGui_ImplGlfw_Init(GLFWwindow* window, bool install_callbacks, Glfw
     io.SetClipboardTextFn = ImGui_ImplGlfw_SetClipboardText;
     io.GetClipboardTextFn = ImGui_ImplGlfw_GetClipboardText;
     io.ClipboardUserData = g_Window;
-#if defined(_WIN32)
-    io.ImeWindowHandle = (void*)glfwGetWin32Window(g_Window);
-#endif
 
     // Create mouse cursors
     // (By design, on X11 cursors are user configurable and some cursors may be missing. When a cursor doesn't exist,
@@ -208,6 +235,7 @@ static bool ImGui_ImplGlfw_Init(GLFWwindow* window, bool install_callbacks, Glfw
     g_PrevUserCallbackScroll = NULL;
     g_PrevUserCallbackKey = NULL;
     g_PrevUserCallbackChar = NULL;
+    g_PrevUserCallbackMonitor = NULL;
     if (install_callbacks)
     {
         g_InstalledCallbacks = true;
@@ -215,8 +243,22 @@ static bool ImGui_ImplGlfw_Init(GLFWwindow* window, bool install_callbacks, Glfw
         g_PrevUserCallbackScroll = glfwSetScrollCallback(window, ImGui_ImplGlfw_ScrollCallback);
         g_PrevUserCallbackKey = glfwSetKeyCallback(window, ImGui_ImplGlfw_KeyCallback);
         g_PrevUserCallbackChar = glfwSetCharCallback(window, ImGui_ImplGlfw_CharCallback);
+        g_PrevUserCallbackMonitor = glfwSetMonitorCallback(ImGui_ImplGlfw_MonitorCallback);
     }
 
+    // Update monitors the first time (note: monitor callback are broken in GLFW 3.2 and earlier, see github.com/glfw/glfw/issues/784)
+    ImGui_ImplGlfw_UpdateMonitors();
+    glfwSetMonitorCallback(ImGui_ImplGlfw_MonitorCallback);
+
+    // Our mouse update function expect PlatformHandle to be filled for the main viewport
+    ImGuiViewport* main_viewport = ImGui::GetMainViewport();
+    main_viewport->PlatformHandle = (void*)g_Window;
+#ifdef _WIN32
+    main_viewport->PlatformHandleRaw = glfwGetWin32Window(g_Window);
+#endif
+    if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+        ImGui_ImplGlfw_InitPlatformInterface();
+
     g_ClientApi = client_api;
     return true;
 }
@@ -233,6 +275,8 @@ bool ImGui_ImplGlfw_InitForVulkan(GLFWwindow* window, bool install_callbacks)
 
 void ImGui_ImplGlfw_Shutdown()
 {
+    ImGui_ImplGlfw_ShutdownPlatformInterface();
+
     if (g_InstalledCallbacks)
     {
         glfwSetMouseButtonCallback(g_Window, g_PrevUserCallbackMousebutton);
@@ -264,24 +308,63 @@ static void ImGui_ImplGlfw_UpdateMousePosAndButtons()
     // Update mouse position
     const ImVec2 mouse_pos_backup = io.MousePos;
     io.MousePos = ImVec2(-FLT_MAX, -FLT_MAX);
+    io.MouseHoveredViewport = 0;
+    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
+    for (int n = 0; n < platform_io.Viewports.Size; n++)
+    {
+        ImGuiViewport* viewport = platform_io.Viewports[n];
+        GLFWwindow* window = (GLFWwindow*)viewport->PlatformHandle;
+        IM_ASSERT(window != NULL);
 #ifdef __EMSCRIPTEN__
-    const bool focused = true; // Emscripten
+        const bool focused = true;
+        IM_ASSERT(platform_io.Viewports.Size == 1);
 #else
-    const bool focused = glfwGetWindowAttrib(g_Window, GLFW_FOCUSED) != 0;
+        const bool focused = glfwGetWindowAttrib(window, GLFW_FOCUSED) != 0;
 #endif
         if (focused)
         {
             if (io.WantSetMousePos)
             {
-            glfwSetCursorPos(g_Window, (double)mouse_pos_backup.x, (double)mouse_pos_backup.y);
+                glfwSetCursorPos(window, (double)(mouse_pos_backup.x - viewport->Pos.x), (double)(mouse_pos_backup.y - viewport->Pos.y));
             }
             else
             {
                 double mouse_x, mouse_y;
-            glfwGetCursorPos(g_Window, &mouse_x, &mouse_y);
+                glfwGetCursorPos(window, &mouse_x, &mouse_y);
+                if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+                {
+                    // Multi-viewport mode: mouse position in OS absolute coordinates (io.MousePos is (0,0) when the mouse is on the upper-left of the primary monitor)
+                    int window_x, window_y;
+                    glfwGetWindowPos(window, &window_x, &window_y);
+                    io.MousePos = ImVec2((float)mouse_x + window_x, (float)mouse_y + window_y);
+                }
+                else
+                {
+                    // Single viewport mode: mouse position in client window coordinates (io.MousePos is (0,0) when the mouse is on the upper-left corner of the app window)
                     io.MousePos = ImVec2((float)mouse_x, (float)mouse_y);
                 }
             }
+            for (int i = 0; i < IM_ARRAYSIZE(io.MouseDown); i++)
+                io.MouseDown[i] |= glfwGetMouseButton(window, i) != 0;
+        }
+
+        // (Optional) When using multiple viewports: set io.MouseHoveredViewport to the viewport the OS mouse cursor is hovering.
+        // Important: this information is not easy to provide and many high-level windowing library won't be able to provide it correctly, because
+        // - This is _ignoring_ viewports with the ImGuiViewportFlags_NoInputs flag (pass-through windows).
+        // - This is _regardless_ of whether another viewport is focused or being dragged from.
+        // If ImGuiBackendFlags_HasMouseHoveredViewport is not set by the backend, imgui will ignore this field and infer the information by relying on the
+        // rectangles and last focused time of every viewports it knows about. It will be unaware of other windows that may be sitting between or over your windows.
+        // [GLFW] FIXME: This is currently only correct on Win32. See what we do below with the WM_NCHITTEST, missing an equivalent for other systems.
+        // See https://github.com/glfw/glfw/issues/1236 if you want to help in making this a GLFW feature.
+#if GLFW_HAS_MOUSE_PASSTHROUGH || (GLFW_HAS_WINDOW_HOVERED && defined(_WIN32))
+        const bool window_no_input = (viewport->Flags & ImGuiViewportFlags_NoInputs) != 0;
+#if GLFW_HAS_MOUSE_PASSTHROUGH
+        glfwSetWindowAttrib(window, GLFW_MOUSE_PASSTHROUGH, window_no_input);
+#endif
+        if (glfwGetWindowAttrib(window, GLFW_HOVERED) && !window_no_input)
+            io.MouseHoveredViewport = viewport->ID;
+#endif
+    }
 }
 
 static void ImGui_ImplGlfw_UpdateMouseCursor()
@@ -291,17 +374,22 @@ static void ImGui_ImplGlfw_UpdateMouseCursor()
         return;
 
     ImGuiMouseCursor imgui_cursor = ImGui::GetMouseCursor();
+    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
+    for (int n = 0; n < platform_io.Viewports.Size; n++)
+    {
+        GLFWwindow* window = (GLFWwindow*)platform_io.Viewports[n]->PlatformHandle;
         if (imgui_cursor == ImGuiMouseCursor_None || io.MouseDrawCursor)
         {
             // Hide OS mouse cursor if imgui is drawing it or if it wants no cursor
-        glfwSetInputMode(g_Window, GLFW_CURSOR, GLFW_CURSOR_HIDDEN);
+            glfwSetInputMode(window, GLFW_CURSOR, GLFW_CURSOR_HIDDEN);
         }
         else
         {
             // Show OS mouse cursor
             // FIXME-PLATFORM: Unfocused windows seems to fail changing the mouse cursor with GLFW 3.2, but 3.3 works here.
-        glfwSetCursor(g_Window, g_MouseCursors[imgui_cursor] ? g_MouseCursors[imgui_cursor] : g_MouseCursors[ImGuiMouseCursor_Arrow]);
-        glfwSetInputMode(g_Window, GLFW_CURSOR, GLFW_CURSOR_NORMAL);
+            glfwSetCursor(window, g_MouseCursors[imgui_cursor] ? g_MouseCursors[imgui_cursor] : g_MouseCursors[ImGuiMouseCursor_Arrow]);
+            glfwSetInputMode(window, GLFW_CURSOR, GLFW_CURSOR_NORMAL);
+        }
     }
 }
 
@@ -342,6 +430,40 @@ static void ImGui_ImplGlfw_UpdateGamepads()
         io.BackendFlags &= ~ImGuiBackendFlags_HasGamepad;
 }
 
+static void ImGui_ImplGlfw_UpdateMonitors()
+{
+    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
+    int monitors_count = 0;
+    GLFWmonitor** glfw_monitors = glfwGetMonitors(&monitors_count);
+    platform_io.Monitors.resize(0);
+    for (int n = 0; n < monitors_count; n++)
+    {
+        ImGuiPlatformMonitor monitor;
+        int x, y;
+        glfwGetMonitorPos(glfw_monitors[n], &x, &y);
+        const GLFWvidmode* vid_mode = glfwGetVideoMode(glfw_monitors[n]);
+        monitor.MainPos = monitor.WorkPos = ImVec2((float)x, (float)y);
+        monitor.MainSize = monitor.WorkSize = ImVec2((float)vid_mode->width, (float)vid_mode->height);
+#if GLFW_HAS_MONITOR_WORK_AREA
+        int w, h;
+        glfwGetMonitorWorkarea(glfw_monitors[n], &x, &y, &w, &h);
+        if (w > 0 && h > 0) // Workaround a small GLFW issue reporting zero on monitor changes: https://github.com/glfw/glfw/pull/1761
+        {
+            monitor.WorkPos = ImVec2((float)x, (float)y);
+            monitor.WorkSize = ImVec2((float)w, (float)h);
+        }
+#endif
+#if GLFW_HAS_PER_MONITOR_DPI
+        // Warning: the validity of monitor DPI information on Windows depends on the application DPI awareness settings, which generally needs to be set in the manifest or at runtime.
+        float x_scale, y_scale;
+        glfwGetMonitorContentScale(glfw_monitors[n], &x_scale, &y_scale);
+        monitor.DpiScale = x_scale;
+#endif
+        platform_io.Monitors.push_back(monitor);
+    }
+    g_WantUpdateMonitors = false;
+}
+
 void ImGui_ImplGlfw_NewFrame()
 {
     ImGuiIO& io = ImGui::GetIO();
@@ -355,6 +477,8 @@ void ImGui_ImplGlfw_NewFrame()
     io.DisplaySize = ImVec2((float)w, (float)h);
     if (w > 0 && h > 0)
         io.DisplayFramebufferScale = ImVec2((float)display_w / w, (float)display_h / h);
+    if (g_WantUpdateMonitors)
+        ImGui_ImplGlfw_UpdateMonitors();
 
     // Setup time step
     double current_time = glfwGetTime();
@@ -367,3 +491,368 @@ void ImGui_ImplGlfw_NewFrame()
     // Update game controllers (if enabled and available)
     ImGui_ImplGlfw_UpdateGamepads();
 }
+
+//--------------------------------------------------------------------------------------------------------
+// MULTI-VIEWPORT / PLATFORM INTERFACE SUPPORT
+// This is an _advanced_ and _optional_ feature, allowing the backend to create and handle multiple viewports simultaneously.
+// If you are new to dear imgui or creating a new binding for dear imgui, it is recommended that you completely ignore this section first..
+//--------------------------------------------------------------------------------------------------------
+
+// Helper structure we store in the void* RenderUserData field of each ImGuiViewport to easily retrieve our backend data.
+struct ImGuiViewportDataGlfw
+{
+    GLFWwindow* Window;
+    bool        WindowOwned;
+    int         IgnoreWindowPosEventFrame;
+    int         IgnoreWindowSizeEventFrame;
+
+    ImGuiViewportDataGlfw()  { Window = NULL; WindowOwned = false; IgnoreWindowSizeEventFrame = IgnoreWindowPosEventFrame = -1; }
+    ~ImGuiViewportDataGlfw() { IM_ASSERT(Window == NULL); }
+};
+
+static void ImGui_ImplGlfw_WindowCloseCallback(GLFWwindow* window)
+{
+    if (ImGuiViewport* viewport = ImGui::FindViewportByPlatformHandle(window))
+        viewport->PlatformRequestClose = true;
+}
+
+// GLFW may dispatch window pos/size events after calling glfwSetWindowPos()/glfwSetWindowSize().
+// However: depending on the platform the callback may be invoked at different time:
+// - on Windows it appears to be called within the glfwSetWindowPos()/glfwSetWindowSize() call
+// - on Linux it is queued and invoked during glfwPollEvents()
+// Because the event doesn't always fire on glfwSetWindowXXX() we use a frame counter tag to only
+// ignore recent glfwSetWindowXXX() calls.
+static void ImGui_ImplGlfw_WindowPosCallback(GLFWwindow* window, int, int)
+{
+    if (ImGuiViewport* viewport = ImGui::FindViewportByPlatformHandle(window))
+    {
+        if (ImGuiViewportDataGlfw* data = (ImGuiViewportDataGlfw*)viewport->PlatformUserData)
+        {
+            bool ignore_event = (ImGui::GetFrameCount() <= data->IgnoreWindowPosEventFrame + 1);
+            //data->IgnoreWindowPosEventFrame = -1;
+            if (ignore_event)
+                return;
+        }
+        viewport->PlatformRequestMove = true;
+    }
+}
+
+static void ImGui_ImplGlfw_WindowSizeCallback(GLFWwindow* window, int, int)
+{
+    if (ImGuiViewport* viewport = ImGui::FindViewportByPlatformHandle(window))
+    {
+        if (ImGuiViewportDataGlfw* data = (ImGuiViewportDataGlfw*)viewport->PlatformUserData)
+        {
+            bool ignore_event = (ImGui::GetFrameCount() <= data->IgnoreWindowSizeEventFrame + 1);
+            //data->IgnoreWindowSizeEventFrame = -1;
+            if (ignore_event)
+                return;
+        }
+        viewport->PlatformRequestResize = true;
+    }
+}
+
+static void ImGui_ImplGlfw_CreateWindow(ImGuiViewport* viewport)
+{
+    ImGuiViewportDataGlfw* data = IM_NEW(ImGuiViewportDataGlfw)();
+    viewport->PlatformUserData = data;
+
+    // GLFW 3.2 unfortunately always set focus on glfwCreateWindow() if GLFW_VISIBLE is set, regardless of GLFW_FOCUSED
+    // With GLFW 3.3, the hint GLFW_FOCUS_ON_SHOW fixes this problem
+    glfwWindowHint(GLFW_VISIBLE, false);
+    glfwWindowHint(GLFW_FOCUSED, false);
+#if GLFW_HAS_FOCUS_ON_SHOW
+     glfwWindowHint(GLFW_FOCUS_ON_SHOW, false);
+ #endif
+    glfwWindowHint(GLFW_DECORATED, (viewport->Flags & ImGuiViewportFlags_NoDecoration) ? false : true);
+#if GLFW_HAS_WINDOW_TOPMOST
+    glfwWindowHint(GLFW_FLOATING, (viewport->Flags & ImGuiViewportFlags_TopMost) ? true : false);
+#endif
+    GLFWwindow* share_window = (g_ClientApi == GlfwClientApi_OpenGL) ? g_Window : NULL;
+    data->Window = glfwCreateWindow((int)viewport->Size.x, (int)viewport->Size.y, "No Title Yet", NULL, share_window);
+    data->WindowOwned = true;
+    viewport->PlatformHandle = (void*)data->Window;
+#ifdef _WIN32
+    viewport->PlatformHandleRaw = glfwGetWin32Window(data->Window);
+#endif
+    glfwSetWindowPos(data->Window, (int)viewport->Pos.x, (int)viewport->Pos.y);
+
+    // Install GLFW callbacks for secondary viewports
+    glfwSetMouseButtonCallback(data->Window, ImGui_ImplGlfw_MouseButtonCallback);
+    glfwSetScrollCallback(data->Window, ImGui_ImplGlfw_ScrollCallback);
+    glfwSetKeyCallback(data->Window, ImGui_ImplGlfw_KeyCallback);
+    glfwSetCharCallback(data->Window, ImGui_ImplGlfw_CharCallback);
+    glfwSetWindowCloseCallback(data->Window, ImGui_ImplGlfw_WindowCloseCallback);
+    glfwSetWindowPosCallback(data->Window, ImGui_ImplGlfw_WindowPosCallback);
+    glfwSetWindowSizeCallback(data->Window, ImGui_ImplGlfw_WindowSizeCallback);
+    if (g_ClientApi == GlfwClientApi_OpenGL)
+    {
+        glfwMakeContextCurrent(data->Window);
+        glfwSwapInterval(0);
+    }
+}
+
+static void ImGui_ImplGlfw_DestroyWindow(ImGuiViewport* viewport)
+{
+    if (ImGuiViewportDataGlfw* data = (ImGuiViewportDataGlfw*)viewport->PlatformUserData)
+    {
+        if (data->WindowOwned)
+        {
+#if !GLFW_HAS_MOUSE_PASSTHROUGH && GLFW_HAS_WINDOW_HOVERED && defined(_WIN32)
+            HWND hwnd = (HWND)viewport->PlatformHandleRaw;
+            ::RemovePropA(hwnd, "IMGUI_VIEWPORT");
+#endif
+            glfwDestroyWindow(data->Window);
+        }
+        data->Window = NULL;
+        IM_DELETE(data);
+    }
+    viewport->PlatformUserData = viewport->PlatformHandle = NULL;
+}
+
+// We have submitted https://github.com/glfw/glfw/pull/1568 to allow GLFW to support "transparent inputs".
+// In the meanwhile we implement custom per-platform workarounds here (FIXME-VIEWPORT: Implement same work-around for Linux/OSX!)
+#if !GLFW_HAS_MOUSE_PASSTHROUGH && GLFW_HAS_WINDOW_HOVERED && defined(_WIN32)
+static WNDPROC g_GlfwWndProc = NULL;
+static LRESULT CALLBACK WndProcNoInputs(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam)
+{
+    if (msg == WM_NCHITTEST)
+    {
+        // Let mouse pass-through the window. This will allow the backend to set io.MouseHoveredViewport properly (which is OPTIONAL).
+        // The ImGuiViewportFlags_NoInputs flag is set while dragging a viewport, as want to detect the window behind the one we are dragging.
+        // If you cannot easily access those viewport flags from your windowing/event code: you may manually synchronize its state e.g. in
+        // your main loop after calling UpdatePlatformWindows(). Iterate all viewports/platform windows and pass the flag to your windowing system.
+        ImGuiViewport* viewport = (ImGuiViewport*)::GetPropA(hWnd, "IMGUI_VIEWPORT");
+        if (viewport->Flags & ImGuiViewportFlags_NoInputs)
+            return HTTRANSPARENT;
+    }
+    return ::CallWindowProc(g_GlfwWndProc, hWnd, msg, wParam, lParam);
+}
+#endif
+
+static void ImGui_ImplGlfw_ShowWindow(ImGuiViewport* viewport)
+{
+    ImGuiViewportDataGlfw* data = (ImGuiViewportDataGlfw*)viewport->PlatformUserData;
+
+#if defined(_WIN32)
+    // GLFW hack: Hide icon from task bar
+    HWND hwnd = (HWND)viewport->PlatformHandleRaw;
+    if (viewport->Flags & ImGuiViewportFlags_NoTaskBarIcon)
+    {
+        LONG ex_style = ::GetWindowLong(hwnd, GWL_EXSTYLE);
+        ex_style &= ~WS_EX_APPWINDOW;
+        ex_style |= WS_EX_TOOLWINDOW;
+        ::SetWindowLong(hwnd, GWL_EXSTYLE, ex_style);
+    }
+
+    // GLFW hack: install hook for WM_NCHITTEST message handler
+#if !GLFW_HAS_MOUSE_PASSTHROUGH && GLFW_HAS_WINDOW_HOVERED && defined(_WIN32)
+    ::SetPropA(hwnd, "IMGUI_VIEWPORT", viewport);
+    if (g_GlfwWndProc == NULL)
+        g_GlfwWndProc = (WNDPROC)::GetWindowLongPtr(hwnd, GWLP_WNDPROC);
+    ::SetWindowLongPtr(hwnd, GWLP_WNDPROC, (LONG_PTR)WndProcNoInputs);
+#endif
+
+#if !GLFW_HAS_FOCUS_ON_SHOW
+    // GLFW hack: GLFW 3.2 has a bug where glfwShowWindow() also activates/focus the window.
+    // The fix was pushed to GLFW repository on 2018/01/09 and should be included in GLFW 3.3 via a GLFW_FOCUS_ON_SHOW window attribute.
+    // See https://github.com/glfw/glfw/issues/1189
+    // FIXME-VIEWPORT: Implement same work-around for Linux/OSX in the meanwhile.
+    if (viewport->Flags & ImGuiViewportFlags_NoFocusOnAppearing)
+    {
+        ::ShowWindow(hwnd, SW_SHOWNA);
+        return;
+    }
+#endif
+#endif
+
+    glfwShowWindow(data->Window);
+}
+
+static ImVec2 ImGui_ImplGlfw_GetWindowPos(ImGuiViewport* viewport)
+{
+    ImGuiViewportDataGlfw* data = (ImGuiViewportDataGlfw*)viewport->PlatformUserData;
+    int x = 0, y = 0;
+    glfwGetWindowPos(data->Window, &x, &y);
+    return ImVec2((float)x, (float)y);
+}
+
+static void ImGui_ImplGlfw_SetWindowPos(ImGuiViewport* viewport, ImVec2 pos)
+{
+    ImGuiViewportDataGlfw* data = (ImGuiViewportDataGlfw*)viewport->PlatformUserData;
+    data->IgnoreWindowPosEventFrame = ImGui::GetFrameCount();
+    glfwSetWindowPos(data->Window, (int)pos.x, (int)pos.y);
+}
+
+static ImVec2 ImGui_ImplGlfw_GetWindowSize(ImGuiViewport* viewport)
+{
+    ImGuiViewportDataGlfw* data = (ImGuiViewportDataGlfw*)viewport->PlatformUserData;
+    int w = 0, h = 0;
+    glfwGetWindowSize(data->Window, &w, &h);
+    return ImVec2((float)w, (float)h);
+}
+
+static void ImGui_ImplGlfw_SetWindowSize(ImGuiViewport* viewport, ImVec2 size)
+{
+    ImGuiViewportDataGlfw* data = (ImGuiViewportDataGlfw*)viewport->PlatformUserData;
+#if __APPLE__ && !GLFW_HAS_OSX_WINDOW_POS_FIX
+    // Native OS windows are positioned from the bottom-left corner on macOS, whereas on other platforms they are
+    // positioned from the upper-left corner. GLFW makes an effort to convert macOS style coordinates, however it
+    // doesn't handle it when changing size. We are manually moving the window in order for changes of size to be based
+    // on the upper-left corner.
+    int x, y, width, height;
+    glfwGetWindowPos(data->Window, &x, &y);
+    glfwGetWindowSize(data->Window, &width, &height);
+    glfwSetWindowPos(data->Window, x, y - height + size.y);
+#endif
+    data->IgnoreWindowSizeEventFrame = ImGui::GetFrameCount();
+    glfwSetWindowSize(data->Window, (int)size.x, (int)size.y);
+}
+
+static void ImGui_ImplGlfw_SetWindowTitle(ImGuiViewport* viewport, const char* title)
+{
+    ImGuiViewportDataGlfw* data = (ImGuiViewportDataGlfw*)viewport->PlatformUserData;
+    glfwSetWindowTitle(data->Window, title);
+}
+
+static void ImGui_ImplGlfw_SetWindowFocus(ImGuiViewport* viewport)
+{
+#if GLFW_HAS_FOCUS_WINDOW
+    ImGuiViewportDataGlfw* data = (ImGuiViewportDataGlfw*)viewport->PlatformUserData;
+    glfwFocusWindow(data->Window);
+#else
+    // FIXME: What are the effect of not having this function? At the moment imgui doesn't actually call SetWindowFocus - we set that up ahead, will answer that question later.
+    (void)viewport;
+#endif
+}
+
+static bool ImGui_ImplGlfw_GetWindowFocus(ImGuiViewport* viewport)
+{
+    ImGuiViewportDataGlfw* data = (ImGuiViewportDataGlfw*)viewport->PlatformUserData;
+    return glfwGetWindowAttrib(data->Window, GLFW_FOCUSED) != 0;
+}
+
+static bool ImGui_ImplGlfw_GetWindowMinimized(ImGuiViewport* viewport)
+{
+    ImGuiViewportDataGlfw* data = (ImGuiViewportDataGlfw*)viewport->PlatformUserData;
+    return glfwGetWindowAttrib(data->Window, GLFW_ICONIFIED) != 0;
+}
+
+#if GLFW_HAS_WINDOW_ALPHA
+static void ImGui_ImplGlfw_SetWindowAlpha(ImGuiViewport* viewport, float alpha)
+{
+    ImGuiViewportDataGlfw* data = (ImGuiViewportDataGlfw*)viewport->PlatformUserData;
+    glfwSetWindowOpacity(data->Window, alpha);
+}
+#endif
+
+static void ImGui_ImplGlfw_RenderWindow(ImGuiViewport* viewport, void*)
+{
+    ImGuiViewportDataGlfw* data = (ImGuiViewportDataGlfw*)viewport->PlatformUserData;
+    if (g_ClientApi == GlfwClientApi_OpenGL)
+        glfwMakeContextCurrent(data->Window);
+}
+
+static void ImGui_ImplGlfw_SwapBuffers(ImGuiViewport* viewport, void*)
+{
+    ImGuiViewportDataGlfw* data = (ImGuiViewportDataGlfw*)viewport->PlatformUserData;
+    if (g_ClientApi == GlfwClientApi_OpenGL)
+    {
+        glfwMakeContextCurrent(data->Window);
+        glfwSwapBuffers(data->Window);
+    }
+}
+
+//--------------------------------------------------------------------------------------------------------
+// IME (Input Method Editor) basic support for e.g. Asian language users
+//--------------------------------------------------------------------------------------------------------
+
+// We provide a Win32 implementation because this is such a common issue for IME users
+#if defined(_WIN32) && !defined(IMGUI_DISABLE_WIN32_FUNCTIONS) && !defined(IMGUI_DISABLE_WIN32_DEFAULT_IME_FUNCTIONS) && !defined(__GNUC__)
+#define HAS_WIN32_IME   1
+#include <imm.h>
+#ifdef _MSC_VER
+#pragma comment(lib, "imm32")
+#endif
+static void ImGui_ImplWin32_SetImeInputPos(ImGuiViewport* viewport, ImVec2 pos)
+{
+    COMPOSITIONFORM cf = { CFS_FORCE_POSITION, { (LONG)(pos.x - viewport->Pos.x), (LONG)(pos.y - viewport->Pos.y) }, { 0, 0, 0, 0 } };
+    if (HWND hwnd = (HWND)viewport->PlatformHandleRaw)
+        if (HIMC himc = ::ImmGetContext(hwnd))
+        {
+            ::ImmSetCompositionWindow(himc, &cf);
+            ::ImmReleaseContext(hwnd, himc);
+        }
+}
+#else
+#define HAS_WIN32_IME   0
+#endif
+
+//--------------------------------------------------------------------------------------------------------
+// Vulkan support (the Vulkan renderer needs to call a platform-side support function to create the surface)
+//--------------------------------------------------------------------------------------------------------
+
+// Avoid including <vulkan.h> so we can build without it
+#if GLFW_HAS_VULKAN
+#ifndef VULKAN_H_
+#define VK_DEFINE_HANDLE(object) typedef struct object##_T* object;
+#if defined(__LP64__) || defined(_WIN64) || defined(__x86_64__) || defined(_M_X64) || defined(__ia64) || defined (_M_IA64) || defined(__aarch64__) || defined(__powerpc64__)
+#define VK_DEFINE_NON_DISPATCHABLE_HANDLE(object) typedef struct object##_T *object;
+#else
+#define VK_DEFINE_NON_DISPATCHABLE_HANDLE(object) typedef uint64_t object;
+#endif
+VK_DEFINE_HANDLE(VkInstance)
+VK_DEFINE_NON_DISPATCHABLE_HANDLE(VkSurfaceKHR)
+struct VkAllocationCallbacks;
+enum VkResult { VK_RESULT_MAX_ENUM = 0x7FFFFFFF };
+#endif // VULKAN_H_
+extern "C" { extern GLFWAPI VkResult glfwCreateWindowSurface(VkInstance instance, GLFWwindow* window, const VkAllocationCallbacks* allocator, VkSurfaceKHR* surface); }
+static int ImGui_ImplGlfw_CreateVkSurface(ImGuiViewport* viewport, ImU64 vk_instance, const void* vk_allocator, ImU64* out_vk_surface)
+{
+    ImGuiViewportDataGlfw* data = (ImGuiViewportDataGlfw*)viewport->PlatformUserData;
+    IM_ASSERT(g_ClientApi == GlfwClientApi_Vulkan);
+    VkResult err = glfwCreateWindowSurface((VkInstance)vk_instance, data->Window, (const VkAllocationCallbacks*)vk_allocator, (VkSurfaceKHR*)out_vk_surface);
+    return (int)err;
+}
+#endif // GLFW_HAS_VULKAN
+
+static void ImGui_ImplGlfw_InitPlatformInterface()
+{
+    // Register platform interface (will be coupled with a renderer interface)
+    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
+    platform_io.Platform_CreateWindow = ImGui_ImplGlfw_CreateWindow;
+    platform_io.Platform_DestroyWindow = ImGui_ImplGlfw_DestroyWindow;
+    platform_io.Platform_ShowWindow = ImGui_ImplGlfw_ShowWindow;
+    platform_io.Platform_SetWindowPos = ImGui_ImplGlfw_SetWindowPos;
+    platform_io.Platform_GetWindowPos = ImGui_ImplGlfw_GetWindowPos;
+    platform_io.Platform_SetWindowSize = ImGui_ImplGlfw_SetWindowSize;
+    platform_io.Platform_GetWindowSize = ImGui_ImplGlfw_GetWindowSize;
+    platform_io.Platform_SetWindowFocus = ImGui_ImplGlfw_SetWindowFocus;
+    platform_io.Platform_GetWindowFocus = ImGui_ImplGlfw_GetWindowFocus;
+    platform_io.Platform_GetWindowMinimized = ImGui_ImplGlfw_GetWindowMinimized;
+    platform_io.Platform_SetWindowTitle = ImGui_ImplGlfw_SetWindowTitle;
+    platform_io.Platform_RenderWindow = ImGui_ImplGlfw_RenderWindow;
+    platform_io.Platform_SwapBuffers = ImGui_ImplGlfw_SwapBuffers;
+#if GLFW_HAS_WINDOW_ALPHA
+    platform_io.Platform_SetWindowAlpha = ImGui_ImplGlfw_SetWindowAlpha;
+#endif
+#if GLFW_HAS_VULKAN
+    platform_io.Platform_CreateVkSurface = ImGui_ImplGlfw_CreateVkSurface;
+#endif
+#if HAS_WIN32_IME
+    platform_io.Platform_SetImeInputPos = ImGui_ImplWin32_SetImeInputPos;
+#endif
+
+    // Register main window handle (which is owned by the main application, not by us)
+    // This is mostly for simplicity and consistency, so that our code (e.g. mouse handling etc.) can use same logic for main and secondary viewports.
+    ImGuiViewport* main_viewport = ImGui::GetMainViewport();
+    ImGuiViewportDataGlfw* data = IM_NEW(ImGuiViewportDataGlfw)();
+    data->Window = g_Window;
+    data->WindowOwned = false;
+    main_viewport->PlatformUserData = data;
+    main_viewport->PlatformHandle = (void*)g_Window;
+}
+
+static void ImGui_ImplGlfw_ShutdownPlatformInterface()
+{
+}

backends/imgui_impl_glfw.h

@@ -7,6 +7,10 @@
 //  [X] Platform: Gamepad support. Enable with 'io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad'.
 //  [x] Platform: Mouse cursor shape and visibility. Disable with 'io.ConfigFlags |= ImGuiConfigFlags_NoMouseCursorChange'. FIXME: 3 cursors types are missing from GLFW.
 //  [X] Platform: Keyboard arrays indexed using GLFW_KEY_* codes, e.g. ImGui::IsKeyPressed(GLFW_KEY_SPACE).
+//  [X] Platform: Multi-viewport support (multiple windows). Enable with 'io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable'.
+
+// Issues:
+//  [ ] Platform: Multi-viewport support: ParentViewportID not honored, and so io.ConfigViewportsNoDefaultParent has no effect (minor).
 
 // You can copy and use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
 // If you are new to Dear ImGui, read documentation from the docs/ folder + read the top of imgui.cpp.
@@ -20,6 +24,7 @@
 #include "imgui.h"      // IMGUI_IMPL_API
 
 struct GLFWwindow;
+struct GLFWmonitor;
 
 IMGUI_IMPL_API bool     ImGui_ImplGlfw_InitForOpenGL(GLFWwindow* window, bool install_callbacks);
 IMGUI_IMPL_API bool     ImGui_ImplGlfw_InitForVulkan(GLFWwindow* window, bool install_callbacks);
@@ -33,3 +38,4 @@ IMGUI_IMPL_API void     ImGui_ImplGlfw_MouseButtonCallback(GLFWwindow* window, i
 IMGUI_IMPL_API void     ImGui_ImplGlfw_ScrollCallback(GLFWwindow* window, double xoffset, double yoffset);
 IMGUI_IMPL_API void     ImGui_ImplGlfw_KeyCallback(GLFWwindow* window, int key, int scancode, int action, int mods);
 IMGUI_IMPL_API void     ImGui_ImplGlfw_CharCallback(GLFWwindow* window, unsigned int c);
+IMGUI_IMPL_API void     ImGui_ImplGlfw_MonitorCallback(GLFWmonitor* monitor, int event);

backends/imgui_impl_glut.cpp

@@ -1,8 +1,8 @@
 // dear imgui: Platform Backend for GLUT/FreeGLUT
 // This needs to be used along with a Renderer (e.g. OpenGL2)
 
-// !!! GLUT/FreeGLUT IS OBSOLETE PREHISTORIC SOFTWARE. Using GLUT is not recommended unless you really miss the 90's. !!!
-// !!! If someone or something is teaching you GLUT today, you are being abused. Please show some resistance. !!!
+// !!! GLUT/FreeGLUT IS OBSOLETE SOFTWARE. Using GLUT is not recommended unless you really miss the 90's. !!!
+// !!! If someone or something is teaching you GLUT in 2020, you are being abused. Please show some resistance. !!!
 // !!! Nowadays, prefer using GLFW or SDL instead!
 
 // Issues:

backends/imgui_impl_glut.h

@@ -1,8 +1,8 @@
 // dear imgui: Platform Backend for GLUT/FreeGLUT
 // This needs to be used along with a Renderer (e.g. OpenGL2)
 
-// !!! GLUT/FreeGLUT IS OBSOLETE PREHISTORIC SOFTWARE. Using GLUT is not recommended unless you really miss the 90's. !!!
-// !!! If someone or something is teaching you GLUT today, you are being abused. Please show some resistance. !!!
+// !!! GLUT/FreeGLUT IS OBSOLETE SOFTWARE. Using GLUT is not recommended unless you really miss the 90's. !!!
+// !!! If someone or something is teaching you GLUT in 2020, you are being abused. Please show some resistance. !!!
 // !!! Nowadays, prefer using GLFW or SDL instead!
 
 // Issues:

backends/imgui_impl_metal.h

@@ -4,6 +4,8 @@
 // Implemented features:
 //  [X] Renderer: User texture binding. Use 'MTLTexture' as ImTextureID. Read the FAQ about ImTextureID!
 //  [X] Renderer: Support for large meshes (64k+ vertices) with 16-bit indices.
+// Missing features:
+//  [ ] Renderer: Multi-viewport / platform windows.
 
 // You can copy and use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
 // If you are new to Dear ImGui, read documentation from the docs/ folder + read the top of imgui.cpp.

backends/imgui_impl_metal.mm

@@ -4,6 +4,8 @@
 // Implemented features:
 //  [X] Renderer: User texture binding. Use 'MTLTexture' as ImTextureID. Read the FAQ about ImTextureID!
 //  [X] Renderer: Support for large meshes (64k+ vertices) with 16-bit indices.
+// Missing features:
+//  [ ] Renderer: Multi-viewport / platform windows.
 
 // You can copy and use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
 // If you are new to Dear ImGui, read documentation from the docs/ folder + read the top of imgui.cpp.

backends/imgui_impl_opengl2.cpp

@@ -3,6 +3,7 @@
 
 // Implemented features:
 //  [X] Renderer: User texture binding. Use 'GLuint' OpenGL texture identifier as void*/ImTextureID. Read the FAQ about ImTextureID!
+//  [X] Renderer: Multi-viewport support. Enable with 'io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable'.
 
 // You can copy and use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
 // If you are new to Dear ImGui, read documentation from the docs/ folder + read the top of imgui.cpp.
@@ -18,8 +19,8 @@
 
 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
-//  2021-01-03: OpenGL: Backup, setup and restore GL_SHADE_MODEL state, disable GL_STENCIL_TEST and disable GL_NORMAL_ARRAY client state to increase compatibility with legacy OpenGL applications.
-//  2020-01-23: OpenGL: Backup, setup and restore GL_TEXTURE_ENV to increase compatibility with legacy OpenGL applications.
+//  2020-XX-XX: Platform: Added support for multiple windows via the ImGuiPlatformIO interface.
+//  2020-01-23: OpenGL: Explicitly backup, setup and restore GL_TEXTURE_ENV to increase compatibility with legacy OpenGL applications.
 //  2019-04-30: OpenGL: Added support for special ImDrawCallback_ResetRenderState callback to reset render state.
 //  2019-02-11: OpenGL: Projecting clipping rectangles correctly using draw_data->FramebufferScale to allow multi-viewports for retina display.
 //  2018-11-30: Misc: Setting up io.BackendRendererName so it can be displayed in the About Window.
@@ -56,17 +57,26 @@
 // OpenGL Data
 static GLuint       g_FontTexture = 0;
 
+// Forward Declarations
+static void ImGui_ImplOpenGL2_InitPlatformInterface();
+static void ImGui_ImplOpenGL2_ShutdownPlatformInterface();
+
 // Functions
 bool    ImGui_ImplOpenGL2_Init()
 {
     // Setup backend capabilities flags
     ImGuiIO& io = ImGui::GetIO();
     io.BackendRendererName = "imgui_impl_opengl2";
+    io.BackendFlags |= ImGuiBackendFlags_RendererHasViewports;    // We can create multi-viewports on the Renderer side (optional)
+
+    if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+        ImGui_ImplOpenGL2_InitPlatformInterface();
     return true;
 }
 
 void    ImGui_ImplOpenGL2_Shutdown()
 {
+    ImGui_ImplOpenGL2_ShutdownPlatformInterface();
     ImGui_ImplOpenGL2_DestroyDeviceObjects();
 }
 
@@ -83,29 +93,23 @@ static void ImGui_ImplOpenGL2_SetupRenderState(ImDrawData* draw_data, int fb_wid
     glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
     glDisable(GL_CULL_FACE);
     glDisable(GL_DEPTH_TEST);
-    glDisable(GL_STENCIL_TEST);
     glDisable(GL_LIGHTING);
     glDisable(GL_COLOR_MATERIAL);
     glEnable(GL_SCISSOR_TEST);
     glEnableClientState(GL_VERTEX_ARRAY);
     glEnableClientState(GL_TEXTURE_COORD_ARRAY);
     glEnableClientState(GL_COLOR_ARRAY);
-    glDisableClientState(GL_NORMAL_ARRAY);
     glEnable(GL_TEXTURE_2D);
     glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
-    glShadeModel(GL_SMOOTH);
     glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
 
     // If you are using this code with non-legacy OpenGL header/contexts (which you should not, prefer using imgui_impl_opengl3.cpp!!),
-    // you may need to backup/reset/restore other state, e.g. for current shader using the commented lines below.
-    // (DO NOT MODIFY THIS FILE! Add the code in your calling function)
+    // you may need to backup/reset/restore current shader using the lines below. DO NOT MODIFY THIS FILE! Add the code in your calling function:
     //  GLint last_program;
     //  glGetIntegerv(GL_CURRENT_PROGRAM, &last_program);
     //  glUseProgram(0);
     //  ImGui_ImplOpenGL2_RenderDrawData(...);
     //  glUseProgram(last_program)
-    // There are potentially many more states you could need to clear/setup that we can't access from default headers.
-    // e.g. glBindBuffer(GL_ARRAY_BUFFER, 0), glDisable(GL_TEXTURE_CUBE_MAP).
 
     // Setup viewport, orthographic projection matrix
     // Our visible imgui space lies from draw_data->DisplayPos (top left) to draw_data->DisplayPos+data_data->DisplaySize (bottom right). DisplayPos is (0,0) for single viewport apps.
@@ -135,7 +139,6 @@ void ImGui_ImplOpenGL2_RenderDrawData(ImDrawData* draw_data)
     GLint last_polygon_mode[2]; glGetIntegerv(GL_POLYGON_MODE, last_polygon_mode);
     GLint last_viewport[4]; glGetIntegerv(GL_VIEWPORT, last_viewport);
     GLint last_scissor_box[4]; glGetIntegerv(GL_SCISSOR_BOX, last_scissor_box);
-    GLint last_shade_model; glGetIntegerv(GL_SHADE_MODEL, &last_shade_model);
     GLint last_tex_env_mode; glGetTexEnviv(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, &last_tex_env_mode);
     glPushAttrib(GL_ENABLE_BIT | GL_COLOR_BUFFER_BIT | GL_TRANSFORM_BIT);
 
@@ -204,7 +207,6 @@ void ImGui_ImplOpenGL2_RenderDrawData(ImDrawData* draw_data)
     glPolygonMode(GL_FRONT, (GLenum)last_polygon_mode[0]); glPolygonMode(GL_BACK, (GLenum)last_polygon_mode[1]);
     glViewport(last_viewport[0], last_viewport[1], (GLsizei)last_viewport[2], (GLsizei)last_viewport[3]);
     glScissor(last_scissor_box[0], last_scissor_box[1], (GLsizei)last_scissor_box[2], (GLsizei)last_scissor_box[3]);
-    glShadeModel(last_shade_model);
     glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, last_tex_env_mode);
 }
 
@@ -255,3 +257,31 @@ void    ImGui_ImplOpenGL2_DestroyDeviceObjects()
 {
     ImGui_ImplOpenGL2_DestroyFontsTexture();
 }
+
+//--------------------------------------------------------------------------------------------------------
+// MULTI-VIEWPORT / PLATFORM INTERFACE SUPPORT
+// This is an _advanced_ and _optional_ feature, allowing the backend to create and handle multiple viewports simultaneously.
+// If you are new to dear imgui or creating a new binding for dear imgui, it is recommended that you completely ignore this section first..
+//--------------------------------------------------------------------------------------------------------
+
+static void ImGui_ImplOpenGL2_RenderWindow(ImGuiViewport* viewport, void*)
+{
+    if (!(viewport->Flags & ImGuiViewportFlags_NoRendererClear))
+    {
+        ImVec4 clear_color = ImVec4(0.0f, 0.0f, 0.0f, 1.0f);
+        glClearColor(clear_color.x, clear_color.y, clear_color.z, clear_color.w);
+        glClear(GL_COLOR_BUFFER_BIT);
+    }
+    ImGui_ImplOpenGL2_RenderDrawData(viewport->DrawData);
+}
+
+static void ImGui_ImplOpenGL2_InitPlatformInterface()
+{
+    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
+    platform_io.Renderer_RenderWindow = ImGui_ImplOpenGL2_RenderWindow;
+}
+
+static void ImGui_ImplOpenGL2_ShutdownPlatformInterface()
+{
+    ImGui::DestroyPlatformWindows();
+}

backends/imgui_impl_opengl2.h

@@ -3,6 +3,7 @@
 
 // Implemented features:
 //  [X] Renderer: User texture binding. Use 'GLuint' OpenGL texture identifier as void*/ImTextureID. Read the FAQ about ImTextureID!
+//  [X] Renderer: Multi-viewport support. Enable with 'io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable'.
 
 // You can copy and use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
 // If you are new to Dear ImGui, read documentation from the docs/ folder + read the top of imgui.cpp.

backends/imgui_impl_opengl3.cpp

@@ -5,6 +5,7 @@
 
 // Implemented features:
 //  [X] Renderer: User texture binding. Use 'GLuint' OpenGL texture identifier as void*/ImTextureID. Read the FAQ about ImTextureID!
+//  [X] Renderer: Multi-viewport support. Enable with 'io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable'.
 //  [x] Renderer: Desktop GL only: Support for large meshes (64k+ vertices) with 16-bit indices.
 
 // You can copy and use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
@@ -13,8 +14,8 @@
 
 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
-//  2021-01-03: OpenGL: Backup, setup and restore GL_STENCIL_TEST state.
-//  2020-10-23: OpenGL: Backup, setup and restore GL_PRIMITIVE_RESTART state.
+//  2020-XX-XX: Platform: Added support for multiple windows via the ImGuiPlatformIO interface.
+//  2020-10-23: OpenGL: Save and restore current GL_PRIMITIVE_RESTART state.
 //  2020-10-15: OpenGL: Use glGetString(GL_VERSION) instead of glGetIntegerv(GL_MAJOR_VERSION, ...) when the later returns zero (e.g. Desktop GL 2.x)
 //  2020-09-17: OpenGL: Fix to avoid compiling/calling glBindSampler() on ES or pre 3.3 context which have the defines set by a loader.
 //  2020-07-10: OpenGL: Added support for glad2 OpenGL loader.
@@ -150,6 +151,10 @@ static GLint        g_AttribLocationTex = 0, g_AttribLocationProjMtx = 0;
 static GLuint       g_AttribLocationVtxPos = 0, g_AttribLocationVtxUV = 0, g_AttribLocationVtxColor = 0; // Vertex attributes location
 static unsigned int g_VboHandle = 0, g_ElementsHandle = 0;
 
+// Forward Declarations
+static void ImGui_ImplOpenGL3_InitPlatformInterface();
+static void ImGui_ImplOpenGL3_ShutdownPlatformInterface();
+
 // Functions
 bool    ImGui_ImplOpenGL3_Init(const char* glsl_version)
 {
@@ -177,6 +182,7 @@ bool    ImGui_ImplOpenGL3_Init(const char* glsl_version)
     if (g_GlVersion >= 320)
         io.BackendFlags |= ImGuiBackendFlags_RendererHasVtxOffset;  // We can honor the ImDrawCmd::VtxOffset field, allowing for large meshes.
 #endif
+    io.BackendFlags |= ImGuiBackendFlags_RendererHasViewports;  // We can create multi-viewports on the Renderer side (optional)
 
     // Store GLSL version string so we can refer to it later in case we recreate shaders.
     // Note: GLSL version is NOT the same as GL version. Leave this to NULL if unsure.
@@ -228,11 +234,15 @@ bool    ImGui_ImplOpenGL3_Init(const char* glsl_version)
     GLint current_texture;
     glGetIntegerv(GL_TEXTURE_BINDING_2D, &current_texture);
 
+    if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+        ImGui_ImplOpenGL3_InitPlatformInterface();
+
     return true;
 }
 
 void    ImGui_ImplOpenGL3_Shutdown()
 {
+    ImGui_ImplOpenGL3_ShutdownPlatformInterface();
     ImGui_ImplOpenGL3_DestroyDeviceObjects();
 }
 
@@ -250,7 +260,6 @@ static void ImGui_ImplOpenGL3_SetupRenderState(ImDrawData* draw_data, int fb_wid
     glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
     glDisable(GL_CULL_FACE);
     glDisable(GL_DEPTH_TEST);
-    glDisable(GL_STENCIL_TEST);
     glEnable(GL_SCISSOR_TEST);
 #ifdef IMGUI_IMPL_OPENGL_MAY_HAVE_PRIMITIVE_RESTART
     if (g_GlVersion >= 310)
@@ -261,8 +270,8 @@ static void ImGui_ImplOpenGL3_SetupRenderState(ImDrawData* draw_data, int fb_wid
 #endif
 
     // Support for GL 4.5 rarely used glClipControl(GL_UPPER_LEFT)
-#if defined(GL_CLIP_ORIGIN) && !defined(__APPLE__)
     bool clip_origin_lower_left = true;
+#if defined(GL_CLIP_ORIGIN) && !defined(__APPLE__)
     GLenum current_clip_origin = 0; glGetIntegerv(GL_CLIP_ORIGIN, (GLint*)&current_clip_origin);
     if (current_clip_origin == GL_UPPER_LEFT)
         clip_origin_lower_left = false;
@@ -275,9 +284,7 @@ static void ImGui_ImplOpenGL3_SetupRenderState(ImDrawData* draw_data, int fb_wid
     float R = draw_data->DisplayPos.x + draw_data->DisplaySize.x;
     float T = draw_data->DisplayPos.y;
     float B = draw_data->DisplayPos.y + draw_data->DisplaySize.y;
-#if defined(GL_CLIP_ORIGIN) && !defined(__APPLE__)
     if (!clip_origin_lower_left) { float tmp = T; T = B; B = tmp; } // Swap top and bottom if origin is upper left
-#endif
     const float ortho_projection[4][4] =
     {
         { 2.0f/(R-L),   0.0f,         0.0f,   0.0f },
@@ -347,7 +354,6 @@ void    ImGui_ImplOpenGL3_RenderDrawData(ImDrawData* draw_data)
     GLboolean last_enable_blend = glIsEnabled(GL_BLEND);
     GLboolean last_enable_cull_face = glIsEnabled(GL_CULL_FACE);
     GLboolean last_enable_depth_test = glIsEnabled(GL_DEPTH_TEST);
-    GLboolean last_enable_stencil_test = glIsEnabled(GL_STENCIL_TEST);
     GLboolean last_enable_scissor_test = glIsEnabled(GL_SCISSOR_TEST);
 #ifdef IMGUI_IMPL_OPENGL_MAY_HAVE_PRIMITIVE_RESTART
     GLboolean last_enable_primitive_restart = (g_GlVersion >= 310) ? glIsEnabled(GL_PRIMITIVE_RESTART) : GL_FALSE;
@@ -436,7 +442,6 @@ void    ImGui_ImplOpenGL3_RenderDrawData(ImDrawData* draw_data)
     if (last_enable_blend) glEnable(GL_BLEND); else glDisable(GL_BLEND);
     if (last_enable_cull_face) glEnable(GL_CULL_FACE); else glDisable(GL_CULL_FACE);
     if (last_enable_depth_test) glEnable(GL_DEPTH_TEST); else glDisable(GL_DEPTH_TEST);
-    if (last_enable_stencil_test) glEnable(GL_STENCIL_TEST); else glDisable(GL_STENCIL_TEST);
     if (last_enable_scissor_test) glEnable(GL_SCISSOR_TEST); else glDisable(GL_SCISSOR_TEST);
 #ifdef IMGUI_IMPL_OPENGL_MAY_HAVE_PRIMITIVE_RESTART
     if (g_GlVersion >= 310) { if (last_enable_primitive_restart) glEnable(GL_PRIMITIVE_RESTART); else glDisable(GL_PRIMITIVE_RESTART); }
@@ -717,3 +722,31 @@ void    ImGui_ImplOpenGL3_DestroyDeviceObjects()
 
     ImGui_ImplOpenGL3_DestroyFontsTexture();
 }
+
+//--------------------------------------------------------------------------------------------------------
+// MULTI-VIEWPORT / PLATFORM INTERFACE SUPPORT
+// This is an _advanced_ and _optional_ feature, allowing the backend to create and handle multiple viewports simultaneously.
+// If you are new to dear imgui or creating a new binding for dear imgui, it is recommended that you completely ignore this section first..
+//--------------------------------------------------------------------------------------------------------
+
+static void ImGui_ImplOpenGL3_RenderWindow(ImGuiViewport* viewport, void*)
+{
+    if (!(viewport->Flags & ImGuiViewportFlags_NoRendererClear))
+    {
+        ImVec4 clear_color = ImVec4(0.0f, 0.0f, 0.0f, 1.0f);
+        glClearColor(clear_color.x, clear_color.y, clear_color.z, clear_color.w);
+        glClear(GL_COLOR_BUFFER_BIT);
+    }
+    ImGui_ImplOpenGL3_RenderDrawData(viewport->DrawData);
+}
+
+static void ImGui_ImplOpenGL3_InitPlatformInterface()
+{
+    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
+    platform_io.Renderer_RenderWindow = ImGui_ImplOpenGL3_RenderWindow;
+}
+
+static void ImGui_ImplOpenGL3_ShutdownPlatformInterface()
+{
+    ImGui::DestroyPlatformWindows();
+}

backends/imgui_impl_opengl3.h

@@ -5,6 +5,7 @@
 
 // Implemented features:
 //  [X] Renderer: User texture binding. Use 'GLuint' OpenGL texture identifier as void*/ImTextureID. Read the FAQ about ImTextureID!
+//  [X] Renderer: Multi-viewport support. Enable with 'io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable'.
 //  [x] Renderer: Desktop GL only: Support for large meshes (64k+ vertices) with 16-bit indices.
 
 // You can copy and use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.

backends/imgui_impl_osx.h

@@ -7,6 +7,7 @@
 //  [X] Platform: OSX clipboard is supported within core Dear ImGui (no specific code in this backend).
 // Issues:
 //  [ ] Platform: Keys are all generally very broken. Best using [event keycode] and not [event characters]..
+//  [ ] Platform: Multi-viewport / platform windows.
 
 // You can copy and use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
 // If you are new to Dear ImGui, read documentation from the docs/ folder + read the top of imgui.cpp.

backends/imgui_impl_osx.mm

@@ -7,6 +7,7 @@
 //  [X] Platform: OSX clipboard is supported within core Dear ImGui (no specific code in this backend).
 // Issues:
 //  [ ] Platform: Keys are all generally very broken. Best using [event keycode] and not [event characters]..
+//  [ ] Platform: Multi-viewport / platform windows.
 
 // You can copy and use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
 // If you are new to Dear ImGui, read documentation from the docs/ folder + read the top of imgui.cpp.

backends/imgui_impl_sdl.cpp

@@ -8,8 +8,10 @@
 //  [X] Platform: Clipboard support.
 //  [X] Platform: Keyboard arrays indexed using SDL_SCANCODE_* codes, e.g. ImGui::IsKeyPressed(SDL_SCANCODE_SPACE).
 //  [X] Platform: Gamepad support. Enabled with 'io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad'.
+//  [X] Platform: Multi-viewport support (multiple windows). Enable with 'io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable'.
 // Missing features:
 //  [ ] Platform: SDL2 handling of IME under Windows appears to be broken and it explicitly disable the regular Windows IME. You can restore Windows IME by compiling SDL with SDL_DISABLE_WINDOWS_IME.
+//  [ ] Platform: Multi-viewport + Minimized windows seems to break mouse wheel events (at least under Windows).
 
 // You can copy and use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
 // If you are new to Dear ImGui, read documentation from the docs/ folder + read the top of imgui.cpp.
@@ -17,6 +19,7 @@
 
 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
+//  2020-XX-XX: Platform: Added support for multiple windows via the ImGuiPlatformIO interface.
 //  2020-05-25: Misc: Report a zero display-size when window is minimized, to be consistent with other backends.
 //  2020-02-20: Inputs: Fixed mapping for ImGuiKey_KeyPadEnter (using SDL_SCANCODE_KP_ENTER instead of SDL_SCANCODE_RETURN2).
 //  2019-12-17: Inputs: On Wayland, use SDL_GetMouseState (because there is no global mouse state).
@@ -48,6 +51,7 @@
 #include "imgui_impl_sdl.h"
 
 // SDL
+// (the multi-viewports feature requires SDL features supported from SDL 2.0.4+. SDL 2.0.5+ is highly recommended)
 #include <SDL.h>
 #include <SDL_syswm.h>
 #if defined(__APPLE__)
@@ -55,7 +59,15 @@
 #endif
 
 #define SDL_HAS_CAPTURE_AND_GLOBAL_MOUSE    SDL_VERSION_ATLEAST(2,0,4)
+#define SDL_HAS_WINDOW_ALPHA                SDL_VERSION_ATLEAST(2,0,5)
+#define SDL_HAS_ALWAYS_ON_TOP               SDL_VERSION_ATLEAST(2,0,5)
+#define SDL_HAS_USABLE_DISPLAY_BOUNDS       SDL_VERSION_ATLEAST(2,0,5)
+#define SDL_HAS_PER_MONITOR_DPI             SDL_VERSION_ATLEAST(2,0,4)
 #define SDL_HAS_VULKAN                      SDL_VERSION_ATLEAST(2,0,6)
+#define SDL_HAS_MOUSE_FOCUS_CLICKTHROUGH    SDL_VERSION_ATLEAST(2,0,5)
+#if !SDL_HAS_VULKAN
+static const Uint32 SDL_WINDOW_VULKAN = 0x10000000;
+#endif
 
 // Data
 static SDL_Window*  g_Window = NULL;
@@ -64,6 +76,12 @@ static bool         g_MousePressed[3] = { false, false, false };
 static SDL_Cursor*  g_MouseCursors[ImGuiMouseCursor_COUNT] = {};
 static char*        g_ClipboardTextData = NULL;
 static bool         g_MouseCanUseGlobalState = true;
+static bool         g_UseVulkan = false;
+
+// Forward Declarations
+static void ImGui_ImplSDL2_UpdateMonitors();
+static void ImGui_ImplSDL2_InitPlatformInterface(SDL_Window* window, void* sdl_gl_context);
+static void ImGui_ImplSDL2_ShutdownPlatformInterface();
 
 static const char* ImGui_ImplSDL2_GetClipboardText(void*)
 {
@@ -124,18 +142,35 @@ bool ImGui_ImplSDL2_ProcessEvent(const SDL_Event* event)
 #endif
             return true;
         }
+    // Multi-viewport support
+    case SDL_WINDOWEVENT:
+        Uint8 window_event = event->window.event;
+        if (window_event == SDL_WINDOWEVENT_CLOSE || window_event == SDL_WINDOWEVENT_MOVED || window_event == SDL_WINDOWEVENT_RESIZED)
+            if (ImGuiViewport* viewport = ImGui::FindViewportByPlatformHandle((void*)SDL_GetWindowFromID(event->window.windowID)))
+            {
+                if (window_event == SDL_WINDOWEVENT_CLOSE)
+                    viewport->PlatformRequestClose = true;
+                if (window_event == SDL_WINDOWEVENT_MOVED)
+                    viewport->PlatformRequestMove = true;
+                if (window_event == SDL_WINDOWEVENT_RESIZED)
+                    viewport->PlatformRequestResize = true;
+                return true;
+            }
+        break;
     }
     return false;
 }
 
-static bool ImGui_ImplSDL2_Init(SDL_Window* window)
+static bool ImGui_ImplSDL2_Init(SDL_Window* window, void* sdl_gl_context)
 {
     g_Window = window;
 
     // Setup backend capabilities flags
     ImGuiIO& io = ImGui::GetIO();
     io.BackendFlags |= ImGuiBackendFlags_HasMouseCursors;       // We can honor GetMouseCursor() values (optional)
-    io.BackendFlags |= ImGuiBackendFlags_HasSetMousePos;        // We can honor io.WantSetMousePos requests (optional, rarely used)
+#if SDL_HAS_CAPTURE_AND_GLOBAL_MOUSE
+    io.BackendFlags |= ImGuiBackendFlags_PlatformHasViewports;  // We can create multi-viewports on the Platform side (optional)
+#endif
     io.BackendPlatformName = "imgui_impl_sdl";
 
     // Keyboard mapping. ImGui will use those indices to peek into the io.KeysDown[] array.
@@ -180,22 +215,31 @@ static bool ImGui_ImplSDL2_Init(SDL_Window* window)
     // Check and store if we are on Wayland
     g_MouseCanUseGlobalState = strncmp(SDL_GetCurrentVideoDriver(), "wayland", 7) != 0;
 
-#ifdef _WIN32
-    SDL_SysWMinfo wmInfo;
-    SDL_VERSION(&wmInfo.version);
-    SDL_GetWindowWMInfo(window, &wmInfo);
-    io.ImeWindowHandle = wmInfo.info.win.window;
-#else
-    (void)window;
+    // Our mouse update function expect PlatformHandle to be filled for the main viewport
+    ImGuiViewport* main_viewport = ImGui::GetMainViewport();
+    main_viewport->PlatformHandle = (void*)window;
+#if defined(_WIN32)
+    SDL_SysWMinfo info;
+    SDL_VERSION(&info.version);
+    if (SDL_GetWindowWMInfo(window, &info))
+        main_viewport->PlatformHandleRaw = info.info.win.window;
 #endif
 
+    // Update monitors
+    ImGui_ImplSDL2_UpdateMonitors();
+
+    // We need SDL_CaptureMouse(), SDL_GetGlobalMouseState() from SDL 2.0.4+ to support multiple viewports.
+    // We left the call to ImGui_ImplSDL2_InitPlatformInterface() outside of #ifdef to avoid unused-function warnings.
+    if ((io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable) && (io.BackendFlags & ImGuiBackendFlags_PlatformHasViewports))
+        ImGui_ImplSDL2_InitPlatformInterface(window, sdl_gl_context);
+
     return true;
 }
 
 bool ImGui_ImplSDL2_InitForOpenGL(SDL_Window* window, void* sdl_gl_context)
 {
     (void)sdl_gl_context; // Viewport branch will need this.
-    return ImGui_ImplSDL2_Init(window);
+    return ImGui_ImplSDL2_Init(window, sdl_gl_context);
 }
 
 bool ImGui_ImplSDL2_InitForVulkan(SDL_Window* window)
@@ -203,7 +247,8 @@ bool ImGui_ImplSDL2_InitForVulkan(SDL_Window* window)
 #if !SDL_HAS_VULKAN
     IM_ASSERT(0 && "Unsupported");
 #endif
-    return ImGui_ImplSDL2_Init(window);
+    g_UseVulkan = true;
+    return ImGui_ImplSDL2_Init(window, NULL);
 }
 
 bool ImGui_ImplSDL2_InitForD3D(SDL_Window* window)
@@ -211,16 +256,17 @@ bool ImGui_ImplSDL2_InitForD3D(SDL_Window* window)
 #if !defined(_WIN32)
     IM_ASSERT(0 && "Unsupported");
 #endif
-    return ImGui_ImplSDL2_Init(window);
+    return ImGui_ImplSDL2_Init(window, NULL);
 }
 
 bool ImGui_ImplSDL2_InitForMetal(SDL_Window* window)
 {
-    return ImGui_ImplSDL2_Init(window);
+    return ImGui_ImplSDL2_Init(window, NULL);
 }
 
 void ImGui_ImplSDL2_Shutdown()
 {
+    ImGui_ImplSDL2_ShutdownPlatformInterface();
     g_Window = NULL;
 
     // Destroy last known clipboard data
@@ -234,39 +280,68 @@ void ImGui_ImplSDL2_Shutdown()
     memset(g_MouseCursors, 0, sizeof(g_MouseCursors));
 }
 
+// This code is incredibly messy because some of the functions we need for full viewport support are not available in SDL < 2.0.4.
 static void ImGui_ImplSDL2_UpdateMousePosAndButtons()
 {
     ImGuiIO& io = ImGui::GetIO();
+    io.MouseHoveredViewport = 0;
 
-    // Set OS mouse position if requested (rarely used, only when ImGuiConfigFlags_NavEnableSetMousePos is enabled by user)
+    // [1]
+    // Only when requested by io.WantSetMousePos: set OS mouse pos from Dear ImGui mouse pos.
+    // (rarely used, mostly when ImGuiConfigFlags_NavEnableSetMousePos is enabled by user)
     if (io.WantSetMousePos)
-        SDL_WarpMouseInWindow(g_Window, (int)io.MousePos.x, (int)io.MousePos.y);
+    {
+#if SDL_HAS_CAPTURE_AND_GLOBAL_MOUSE
+        if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+            SDL_WarpMouseGlobal((int)io.MousePos.x, (int)io.MousePos.y);
         else
+#endif
+            SDL_WarpMouseInWindow(g_Window, (int)io.MousePos.x, (int)io.MousePos.y);
+    }
+    else
+    {
         io.MousePos = ImVec2(-FLT_MAX, -FLT_MAX);
+    }
 
-    int mx, my;
-    Uint32 mouse_buttons = SDL_GetMouseState(&mx, &my);
+    // [2]
+    // Set Dear ImGui mouse pos from OS mouse pos + get buttons. (this is the common behavior)
+    int mouse_x_local, mouse_y_local;
+    Uint32 mouse_buttons = SDL_GetMouseState(&mouse_x_local, &mouse_y_local);
     io.MouseDown[0] = g_MousePressed[0] || (mouse_buttons & SDL_BUTTON(SDL_BUTTON_LEFT)) != 0;      // If a mouse press event came, always pass it as "mouse held this frame", so we don't miss click-release events that are shorter than 1 frame.
     io.MouseDown[1] = g_MousePressed[1] || (mouse_buttons & SDL_BUTTON(SDL_BUTTON_RIGHT)) != 0;
     io.MouseDown[2] = g_MousePressed[2] || (mouse_buttons & SDL_BUTTON(SDL_BUTTON_MIDDLE)) != 0;
     g_MousePressed[0] = g_MousePressed[1] = g_MousePressed[2] = false;
 
 #if SDL_HAS_CAPTURE_AND_GLOBAL_MOUSE && !defined(__EMSCRIPTEN__) && !defined(__ANDROID__) && !(defined(__APPLE__) && TARGET_OS_IOS)
-    SDL_Window* focused_window = SDL_GetKeyboardFocus();
-    if (g_Window == focused_window)
-    {
+
     if (g_MouseCanUseGlobalState)
     {
-            // SDL_GetMouseState() gives mouse position seemingly based on the last window entered/focused(?)
-            // The creation of a new windows at runtime and SDL_CaptureMouse both seems to severely mess up with that, so we retrieve that position globally.
-            // Won't use this workaround when on Wayland, as there is no global mouse position.
-            int wx, wy;
-            SDL_GetWindowPosition(focused_window, &wx, &wy);
-            SDL_GetGlobalMouseState(&mx, &my);
-            mx -= wx;
-            my -= wy;
+        // SDL 2.0.4 and later has SDL_GetGlobalMouseState() and SDL_CaptureMouse()
+        int mouse_x_global, mouse_y_global;
+        SDL_GetGlobalMouseState(&mouse_x_global, &mouse_y_global);
+
+        if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+        {
+            // Multi-viewport mode: mouse position in OS absolute coordinates (io.MousePos is (0,0) when the mouse is on the upper-left of the primary monitor)
+            if (SDL_Window* focused_window = SDL_GetKeyboardFocus())
+                if (ImGui::FindViewportByPlatformHandle((void*)focused_window) != NULL)
+                    io.MousePos = ImVec2((float)mouse_x_global, (float)mouse_y_global);
         }
-        io.MousePos = ImVec2((float)mx, (float)my);
+        else
+        {
+            // Single-viewport mode: mouse position in client window coordinatesio.MousePos is (0,0) when the mouse is on the upper-left corner of the app window)
+            if (SDL_GetWindowFlags(g_Window) & SDL_WINDOW_INPUT_FOCUS)
+            {
+                int window_x, window_y;
+                SDL_GetWindowPosition(g_Window, &window_x, &window_y);
+                io.MousePos = ImVec2((float)(mouse_x_global - window_x), (float)(mouse_y_global - window_y));
+            }
+        }
+    }
+    else
+    {
+        if (SDL_GetWindowFlags(g_Window) & SDL_WINDOW_INPUT_FOCUS)
+            io.MousePos = ImVec2((float)mouse_x_local, (float)mouse_y_local);
     }
 
     // SDL_CaptureMouse() let the OS know e.g. that our imgui drag outside the SDL window boundaries shouldn't e.g. trigger the OS window resize cursor.
@@ -274,8 +349,9 @@ static void ImGui_ImplSDL2_UpdateMousePosAndButtons()
     bool any_mouse_button_down = ImGui::IsAnyMouseDown();
     SDL_CaptureMouse(any_mouse_button_down ? SDL_TRUE : SDL_FALSE);
 #else
+    // SDL 2.0.3 and before: single-viewport only
     if (SDL_GetWindowFlags(g_Window) & SDL_WINDOW_INPUT_FOCUS)
-        io.MousePos = ImVec2((float)mx, (float)my);
+        io.MousePos = ImVec2((float)mouse_x_local, (float)mouse_y_local);
 #endif
 }
 
@@ -340,6 +416,34 @@ static void ImGui_ImplSDL2_UpdateGamepads()
     #undef MAP_ANALOG
 }
 
+// FIXME-PLATFORM: SDL doesn't have an event to notify the application of display/monitor changes
+static void ImGui_ImplSDL2_UpdateMonitors()
+{
+    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
+    platform_io.Monitors.resize(0);
+    int display_count = SDL_GetNumVideoDisplays();
+    for (int n = 0; n < display_count; n++)
+    {
+        // Warning: the validity of monitor DPI information on Windows depends on the application DPI awareness settings, which generally needs to be set in the manifest or at runtime.
+        ImGuiPlatformMonitor monitor;
+        SDL_Rect r;
+        SDL_GetDisplayBounds(n, &r);
+        monitor.MainPos = monitor.WorkPos = ImVec2((float)r.x, (float)r.y);
+        monitor.MainSize = monitor.WorkSize = ImVec2((float)r.w, (float)r.h);
+#if SDL_HAS_USABLE_DISPLAY_BOUNDS
+        SDL_GetDisplayUsableBounds(n, &r);
+        monitor.WorkPos = ImVec2((float)r.x, (float)r.y);
+        monitor.WorkSize = ImVec2((float)r.w, (float)r.h);
+#endif
+#if SDL_HAS_PER_MONITOR_DPI
+        float dpi = 0.0f;
+        if (!SDL_GetDisplayDPI(n, &dpi, NULL, NULL))
+            monitor.DpiScale = dpi / 96.0f;
+#endif
+        platform_io.Monitors.push_back(monitor);
+    }
+}
+
 void ImGui_ImplSDL2_NewFrame(SDL_Window* window)
 {
     ImGuiIO& io = ImGui::GetIO();
@@ -368,3 +472,248 @@ void ImGui_ImplSDL2_NewFrame(SDL_Window* window)
     // Update game controllers (if enabled and available)
     ImGui_ImplSDL2_UpdateGamepads();
 }
+
+//--------------------------------------------------------------------------------------------------------
+// MULTI-VIEWPORT / PLATFORM INTERFACE SUPPORT
+// This is an _advanced_ and _optional_ feature, allowing the backend to create and handle multiple viewports simultaneously.
+// If you are new to dear imgui or creating a new binding for dear imgui, it is recommended that you completely ignore this section first..
+//--------------------------------------------------------------------------------------------------------
+
+// Helper structure we store in the void* RenderUserData field of each ImGuiViewport to easily retrieve our backend data.
+struct ImGuiViewportDataSDL2
+{
+    SDL_Window*     Window;
+    Uint32          WindowID;
+    bool            WindowOwned;
+    SDL_GLContext   GLContext;
+
+    ImGuiViewportDataSDL2() { Window = NULL; WindowID = 0; WindowOwned = false; GLContext = NULL; }
+    ~ImGuiViewportDataSDL2() { IM_ASSERT(Window == NULL && GLContext == NULL); }
+};
+
+static void ImGui_ImplSDL2_CreateWindow(ImGuiViewport* viewport)
+{
+    ImGuiViewportDataSDL2* data = IM_NEW(ImGuiViewportDataSDL2)();
+    viewport->PlatformUserData = data;
+
+    ImGuiViewport* main_viewport = ImGui::GetMainViewport();
+    ImGuiViewportDataSDL2* main_viewport_data = (ImGuiViewportDataSDL2*)main_viewport->PlatformUserData;
+
+    // Share GL resources with main context
+    bool use_opengl = (main_viewport_data->GLContext != NULL);
+    SDL_GLContext backup_context = NULL;
+    if (use_opengl)
+    {
+        backup_context = SDL_GL_GetCurrentContext();
+        SDL_GL_SetAttribute(SDL_GL_SHARE_WITH_CURRENT_CONTEXT, 1);
+        SDL_GL_MakeCurrent(main_viewport_data->Window, main_viewport_data->GLContext);
+    }
+
+    Uint32 sdl_flags = 0;
+    sdl_flags |= use_opengl ? SDL_WINDOW_OPENGL : (g_UseVulkan ? SDL_WINDOW_VULKAN : 0);
+    sdl_flags |= SDL_GetWindowFlags(g_Window) & SDL_WINDOW_ALLOW_HIGHDPI;
+    sdl_flags |= SDL_WINDOW_HIDDEN;
+    sdl_flags |= (viewport->Flags & ImGuiViewportFlags_NoDecoration) ? SDL_WINDOW_BORDERLESS : 0;
+    sdl_flags |= (viewport->Flags & ImGuiViewportFlags_NoDecoration) ? 0 : SDL_WINDOW_RESIZABLE;
+#if !defined(_WIN32)
+    // See SDL hack in ImGui_ImplSDL2_ShowWindow().
+    sdl_flags |= (viewport->Flags & ImGuiViewportFlags_NoTaskBarIcon) ? SDL_WINDOW_SKIP_TASKBAR : 0;
+#endif
+#if SDL_HAS_ALWAYS_ON_TOP
+    sdl_flags |= (viewport->Flags & ImGuiViewportFlags_TopMost) ? SDL_WINDOW_ALWAYS_ON_TOP : 0;
+#endif
+    data->Window = SDL_CreateWindow("No Title Yet", (int)viewport->Pos.x, (int)viewport->Pos.y, (int)viewport->Size.x, (int)viewport->Size.y, sdl_flags);
+    data->WindowOwned = true;
+    if (use_opengl)
+    {
+        data->GLContext = SDL_GL_CreateContext(data->Window);
+        SDL_GL_SetSwapInterval(0);
+    }
+    if (use_opengl && backup_context)
+        SDL_GL_MakeCurrent(data->Window, backup_context);
+
+    viewport->PlatformHandle = (void*)data->Window;
+#if defined(_WIN32)
+    SDL_SysWMinfo info;
+    SDL_VERSION(&info.version);
+    if (SDL_GetWindowWMInfo(data->Window, &info))
+        viewport->PlatformHandleRaw = info.info.win.window;
+#endif
+}
+
+static void ImGui_ImplSDL2_DestroyWindow(ImGuiViewport* viewport)
+{
+    if (ImGuiViewportDataSDL2* data = (ImGuiViewportDataSDL2*)viewport->PlatformUserData)
+    {
+        if (data->GLContext && data->WindowOwned)
+            SDL_GL_DeleteContext(data->GLContext);
+        if (data->Window && data->WindowOwned)
+            SDL_DestroyWindow(data->Window);
+        data->GLContext = NULL;
+        data->Window = NULL;
+        IM_DELETE(data);
+    }
+    viewport->PlatformUserData = viewport->PlatformHandle = NULL;
+}
+
+static void ImGui_ImplSDL2_ShowWindow(ImGuiViewport* viewport)
+{
+    ImGuiViewportDataSDL2* data = (ImGuiViewportDataSDL2*)viewport->PlatformUserData;
+#if defined(_WIN32)
+    HWND hwnd = (HWND)viewport->PlatformHandleRaw;
+
+    // SDL hack: Hide icon from task bar
+    // Note: SDL 2.0.6+ has a SDL_WINDOW_SKIP_TASKBAR flag which is supported under Windows but the way it create the window breaks our seamless transition.
+    if (viewport->Flags & ImGuiViewportFlags_NoTaskBarIcon)
+    {
+        LONG ex_style = ::GetWindowLong(hwnd, GWL_EXSTYLE);
+        ex_style &= ~WS_EX_APPWINDOW;
+        ex_style |= WS_EX_TOOLWINDOW;
+        ::SetWindowLong(hwnd, GWL_EXSTYLE, ex_style);
+    }
+
+    // SDL hack: SDL always activate/focus windows :/
+    if (viewport->Flags & ImGuiViewportFlags_NoFocusOnAppearing)
+    {
+        ::ShowWindow(hwnd, SW_SHOWNA);
+        return;
+    }
+#endif
+
+    SDL_ShowWindow(data->Window);
+}
+
+static ImVec2 ImGui_ImplSDL2_GetWindowPos(ImGuiViewport* viewport)
+{
+    ImGuiViewportDataSDL2* data = (ImGuiViewportDataSDL2*)viewport->PlatformUserData;
+    int x = 0, y = 0;
+    SDL_GetWindowPosition(data->Window, &x, &y);
+    return ImVec2((float)x, (float)y);
+}
+
+static void ImGui_ImplSDL2_SetWindowPos(ImGuiViewport* viewport, ImVec2 pos)
+{
+    ImGuiViewportDataSDL2* data = (ImGuiViewportDataSDL2*)viewport->PlatformUserData;
+    SDL_SetWindowPosition(data->Window, (int)pos.x, (int)pos.y);
+}
+
+static ImVec2 ImGui_ImplSDL2_GetWindowSize(ImGuiViewport* viewport)
+{
+    ImGuiViewportDataSDL2* data = (ImGuiViewportDataSDL2*)viewport->PlatformUserData;
+    int w = 0, h = 0;
+    SDL_GetWindowSize(data->Window, &w, &h);
+    return ImVec2((float)w, (float)h);
+}
+
+static void ImGui_ImplSDL2_SetWindowSize(ImGuiViewport* viewport, ImVec2 size)
+{
+    ImGuiViewportDataSDL2* data = (ImGuiViewportDataSDL2*)viewport->PlatformUserData;
+    SDL_SetWindowSize(data->Window, (int)size.x, (int)size.y);
+}
+
+static void ImGui_ImplSDL2_SetWindowTitle(ImGuiViewport* viewport, const char* title)
+{
+    ImGuiViewportDataSDL2* data = (ImGuiViewportDataSDL2*)viewport->PlatformUserData;
+    SDL_SetWindowTitle(data->Window, title);
+}
+
+#if SDL_HAS_WINDOW_ALPHA
+static void ImGui_ImplSDL2_SetWindowAlpha(ImGuiViewport* viewport, float alpha)
+{
+    ImGuiViewportDataSDL2* data = (ImGuiViewportDataSDL2*)viewport->PlatformUserData;
+    SDL_SetWindowOpacity(data->Window, alpha);
+}
+#endif
+
+static void ImGui_ImplSDL2_SetWindowFocus(ImGuiViewport* viewport)
+{
+    ImGuiViewportDataSDL2* data = (ImGuiViewportDataSDL2*)viewport->PlatformUserData;
+    SDL_RaiseWindow(data->Window);
+}
+
+static bool ImGui_ImplSDL2_GetWindowFocus(ImGuiViewport* viewport)
+{
+    ImGuiViewportDataSDL2* data = (ImGuiViewportDataSDL2*)viewport->PlatformUserData;
+    return (SDL_GetWindowFlags(data->Window) & SDL_WINDOW_INPUT_FOCUS) != 0;
+}
+
+static bool ImGui_ImplSDL2_GetWindowMinimized(ImGuiViewport* viewport)
+{
+    ImGuiViewportDataSDL2* data = (ImGuiViewportDataSDL2*)viewport->PlatformUserData;
+    return (SDL_GetWindowFlags(data->Window) & SDL_WINDOW_MINIMIZED) != 0;
+}
+
+static void ImGui_ImplSDL2_RenderWindow(ImGuiViewport* viewport, void*)
+{
+    ImGuiViewportDataSDL2* data = (ImGuiViewportDataSDL2*)viewport->PlatformUserData;
+    if (data->GLContext)
+        SDL_GL_MakeCurrent(data->Window, data->GLContext);
+}
+
+static void ImGui_ImplSDL2_SwapBuffers(ImGuiViewport* viewport, void*)
+{
+    ImGuiViewportDataSDL2* data = (ImGuiViewportDataSDL2*)viewport->PlatformUserData;
+    if (data->GLContext)
+    {
+        SDL_GL_MakeCurrent(data->Window, data->GLContext);
+        SDL_GL_SwapWindow(data->Window);
+    }
+}
+
+// Vulkan support (the Vulkan renderer needs to call a platform-side support function to create the surface)
+// SDL is graceful enough to _not_ need <vulkan/vulkan.h> so we can safely include this.
+#if SDL_HAS_VULKAN
+#include <SDL_vulkan.h>
+static int ImGui_ImplSDL2_CreateVkSurface(ImGuiViewport* viewport, ImU64 vk_instance, const void* vk_allocator, ImU64* out_vk_surface)
+{
+    ImGuiViewportDataSDL2* data = (ImGuiViewportDataSDL2*)viewport->PlatformUserData;
+    (void)vk_allocator;
+    SDL_bool ret = SDL_Vulkan_CreateSurface(data->Window, (VkInstance)vk_instance, (VkSurfaceKHR*)out_vk_surface);
+    return ret ? 0 : 1; // ret ? VK_SUCCESS : VK_NOT_READY
+}
+#endif // SDL_HAS_VULKAN
+
+static void ImGui_ImplSDL2_InitPlatformInterface(SDL_Window* window, void* sdl_gl_context)
+{
+    // Register platform interface (will be coupled with a renderer interface)
+    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
+    platform_io.Platform_CreateWindow = ImGui_ImplSDL2_CreateWindow;
+    platform_io.Platform_DestroyWindow = ImGui_ImplSDL2_DestroyWindow;
+    platform_io.Platform_ShowWindow = ImGui_ImplSDL2_ShowWindow;
+    platform_io.Platform_SetWindowPos = ImGui_ImplSDL2_SetWindowPos;
+    platform_io.Platform_GetWindowPos = ImGui_ImplSDL2_GetWindowPos;
+    platform_io.Platform_SetWindowSize = ImGui_ImplSDL2_SetWindowSize;
+    platform_io.Platform_GetWindowSize = ImGui_ImplSDL2_GetWindowSize;
+    platform_io.Platform_SetWindowFocus = ImGui_ImplSDL2_SetWindowFocus;
+    platform_io.Platform_GetWindowFocus = ImGui_ImplSDL2_GetWindowFocus;
+    platform_io.Platform_GetWindowMinimized = ImGui_ImplSDL2_GetWindowMinimized;
+    platform_io.Platform_SetWindowTitle = ImGui_ImplSDL2_SetWindowTitle;
+    platform_io.Platform_RenderWindow = ImGui_ImplSDL2_RenderWindow;
+    platform_io.Platform_SwapBuffers = ImGui_ImplSDL2_SwapBuffers;
+#if SDL_HAS_WINDOW_ALPHA
+    platform_io.Platform_SetWindowAlpha = ImGui_ImplSDL2_SetWindowAlpha;
+#endif
+#if SDL_HAS_VULKAN
+    platform_io.Platform_CreateVkSurface = ImGui_ImplSDL2_CreateVkSurface;
+#endif
+
+    // SDL2 by default doesn't pass mouse clicks to the application when the click focused a window. This is getting in the way of our interactions and we disable that behavior.
+#if SDL_HAS_MOUSE_FOCUS_CLICKTHROUGH
+    SDL_SetHint(SDL_HINT_MOUSE_FOCUS_CLICKTHROUGH, "1");
+#endif
+
+    // Register main window handle (which is owned by the main application, not by us)
+    // This is mostly for simplicity and consistency, so that our code (e.g. mouse handling etc.) can use same logic for main and secondary viewports.
+    ImGuiViewport* main_viewport = ImGui::GetMainViewport();
+    ImGuiViewportDataSDL2* data = IM_NEW(ImGuiViewportDataSDL2)();
+    data->Window = window;
+    data->WindowID = SDL_GetWindowID(window);
+    data->WindowOwned = false;
+    data->GLContext = sdl_gl_context;
+    main_viewport->PlatformUserData = data;
+    main_viewport->PlatformHandle = data->Window;
+}
+
+static void ImGui_ImplSDL2_ShutdownPlatformInterface()
+{
+}

backends/imgui_impl_sdl.h

@@ -7,8 +7,10 @@
 //  [X] Platform: Clipboard support.
 //  [X] Platform: Keyboard arrays indexed using SDL_SCANCODE_* codes, e.g. ImGui::IsKeyPressed(SDL_SCANCODE_SPACE).
 //  [X] Platform: Gamepad support. Enabled with 'io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad'.
+//  [X] Platform: Multi-viewport support (multiple windows). Enable with 'io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable'.
 // Missing features:
 //  [ ] Platform: SDL2 handling of IME under Windows appears to be broken and it explicitly disable the regular Windows IME. You can restore Windows IME by compiling SDL with SDL_DISABLE_WINDOWS_IME.
+//  [ ] Platform: Multi-viewport + Minimized windows seems to break mouse wheel events (at least under Windows).
 
 // You can copy and use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
 // If you are new to Dear ImGui, read documentation from the docs/ folder + read the top of imgui.cpp.

backends/imgui_impl_vulkan.cpp

@@ -3,6 +3,7 @@
 
 // Implemented features:
 //  [X] Renderer: Support for large meshes (64k+ vertices) with 16-bit indices.
+//  [x] Platform: Multi-viewport / platform windows. With issues (flickering when creating a new viewport).
 // Missing features:
 //  [ ] Renderer: User texture binding. Changes of ImTextureID aren't supported by this backend! See https://github.com/ocornut/imgui/pull/914
 
@@ -73,6 +74,18 @@ struct ImGui_ImplVulkanH_WindowRenderBuffers
     ImGui_ImplVulkanH_FrameRenderBuffers*   FrameRenderBuffers;
 };
 
+// For multi-viewport support:
+// Helper structure we store in the void* RenderUserData field of each ImGuiViewport to easily retrieve our backend data.
+struct ImGuiViewportDataVulkan
+{
+    bool                                    WindowOwned;
+    ImGui_ImplVulkanH_Window                Window;             // Used by secondary viewports only
+    ImGui_ImplVulkanH_WindowRenderBuffers   RenderBuffers;      // Used by all viewports
+
+    ImGuiViewportDataVulkan() { WindowOwned = false; memset(&RenderBuffers, 0, sizeof(RenderBuffers)); }
+    ~ImGuiViewportDataVulkan() { }
+};
+
 // Vulkan data
 static ImGui_ImplVulkan_InitInfo g_VulkanInitInfo = {};
 static VkRenderPass             g_RenderPass = VK_NULL_HANDLE;
@@ -94,9 +107,6 @@ static VkImageView              g_FontView = VK_NULL_HANDLE;
 static VkDeviceMemory           g_UploadBufferMemory = VK_NULL_HANDLE;
 static VkBuffer                 g_UploadBuffer = VK_NULL_HANDLE;
 
-// Render buffers
-static ImGui_ImplVulkanH_WindowRenderBuffers    g_MainWindowRenderBuffers;
-
 // Forward Declarations
 bool ImGui_ImplVulkan_CreateDeviceObjects();
 void ImGui_ImplVulkan_DestroyDeviceObjects();
@@ -104,6 +114,7 @@ void ImGui_ImplVulkanH_DestroyFrame(VkDevice device, ImGui_ImplVulkanH_Frame* fd
 void ImGui_ImplVulkanH_DestroyFrameSemaphores(VkDevice device, ImGui_ImplVulkanH_FrameSemaphores* fsd, const VkAllocationCallbacks* allocator);
 void ImGui_ImplVulkanH_DestroyFrameRenderBuffers(VkDevice device, ImGui_ImplVulkanH_FrameRenderBuffers* buffers, const VkAllocationCallbacks* allocator);
 void ImGui_ImplVulkanH_DestroyWindowRenderBuffers(VkDevice device, ImGui_ImplVulkanH_WindowRenderBuffers* buffers, const VkAllocationCallbacks* allocator);
+void ImGui_ImplVulkanH_DestroyAllViewportsRenderBuffers(VkDevice device, const VkAllocationCallbacks* allocator);
 void ImGui_ImplVulkanH_CreateWindowSwapChain(VkPhysicalDevice physical_device, VkDevice device, ImGui_ImplVulkanH_Window* wd, const VkAllocationCallbacks* allocator, int w, int h, uint32_t min_image_count);
 void ImGui_ImplVulkanH_CreateWindowCommandBuffers(VkPhysicalDevice physical_device, VkDevice device, ImGui_ImplVulkanH_Window* wd, uint32_t queue_family, const VkAllocationCallbacks* allocator);
 
@@ -111,6 +122,10 @@ void ImGui_ImplVulkanH_CreateWindowCommandBuffers(VkPhysicalDevice physical_devi
 // SHADERS
 //-----------------------------------------------------------------------------
 
+// Forward Declarations
+static void ImGui_ImplVulkan_InitPlatformInterface();
+static void ImGui_ImplVulkan_ShutdownPlatformInterface();
+
 // glsl_shader.vert, compiled with:
 // # glslangValidator -V -x -o glsl_shader.vert.u32 glsl_shader.vert
 /*
@@ -328,8 +343,10 @@ void ImGui_ImplVulkan_RenderDrawData(ImDrawData* draw_data, VkCommandBuffer comm
     if (pipeline == VK_NULL_HANDLE)
         pipeline = g_Pipeline;
 
-    // Allocate array to store enough vertex/index buffers
-    ImGui_ImplVulkanH_WindowRenderBuffers* wrb = &g_MainWindowRenderBuffers;
+    // Allocate array to store enough vertex/index buffers. Each unique viewport gets its own storage.
+    ImGuiViewportDataVulkan* viewport_renderer_data = (ImGuiViewportDataVulkan*)draw_data->OwnerViewport->RendererUserData;
+    IM_ASSERT(viewport_renderer_data != NULL);
+    ImGui_ImplVulkanH_WindowRenderBuffers* wrb = &viewport_renderer_data->RenderBuffers;
     if (wrb->FrameRenderBuffers == NULL)
     {
         wrb->Index = 0;
@@ -872,7 +889,7 @@ void    ImGui_ImplVulkan_DestroyFontUploadObjects()
 void    ImGui_ImplVulkan_DestroyDeviceObjects()
 {
     ImGui_ImplVulkan_InitInfo* v = &g_VulkanInitInfo;
-    ImGui_ImplVulkanH_DestroyWindowRenderBuffers(v->Device, &g_MainWindowRenderBuffers, v->Allocator);
+    ImGui_ImplVulkanH_DestroyAllViewportsRenderBuffers(v->Device, v->Allocator);
     ImGui_ImplVulkan_DestroyFontUploadObjects();
 
     if (g_ShaderModuleVert)     { vkDestroyShaderModule(v->Device, g_ShaderModuleVert, v->Allocator); g_ShaderModuleVert = VK_NULL_HANDLE; }
@@ -892,6 +909,7 @@ bool    ImGui_ImplVulkan_Init(ImGui_ImplVulkan_InitInfo* info, VkRenderPass rend
     ImGuiIO& io = ImGui::GetIO();
     io.BackendRendererName = "imgui_impl_vulkan";
     io.BackendFlags |= ImGuiBackendFlags_RendererHasVtxOffset;  // We can honor the ImDrawCmd::VtxOffset field, allowing for large meshes.
+    io.BackendFlags |= ImGuiBackendFlags_RendererHasViewports;  // We can create multi-viewports on the Renderer side (optional)
 
     IM_ASSERT(info->Instance != VK_NULL_HANDLE);
     IM_ASSERT(info->PhysicalDevice != VK_NULL_HANDLE);
@@ -908,12 +926,29 @@ bool    ImGui_ImplVulkan_Init(ImGui_ImplVulkan_InitInfo* info, VkRenderPass rend
 
     ImGui_ImplVulkan_CreateDeviceObjects();
 
+    // Our render function expect RendererUserData to be storing the window render buffer we need (for the main viewport we won't use ->Window)
+    ImGuiViewport* main_viewport = ImGui::GetMainViewport();
+    main_viewport->RendererUserData = IM_NEW(ImGuiViewportDataVulkan)();
+
+    if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+        ImGui_ImplVulkan_InitPlatformInterface();
+
     return true;
 }
 
 void ImGui_ImplVulkan_Shutdown()
 {
+    // First destroy objects in all viewports
     ImGui_ImplVulkan_DestroyDeviceObjects();
+
+    // Manually delete main viewport render data in-case we haven't initialized for viewports
+    ImGuiViewport* main_viewport = ImGui::GetMainViewport();
+    if (ImGuiViewportDataVulkan* data = (ImGuiViewportDataVulkan*)main_viewport->RendererUserData)
+        IM_DELETE(data);
+    main_viewport->RendererUserData = NULL;
+
+    // Clean up windows
+    ImGui_ImplVulkan_ShutdownPlatformInterface();
 }
 
 void ImGui_ImplVulkan_NewFrame()
@@ -926,10 +961,12 @@ void ImGui_ImplVulkan_SetMinImageCount(uint32_t min_image_count)
     if (g_VulkanInitInfo.MinImageCount == min_image_count)
         return;
 
+    IM_ASSERT(0); // FIXME-VIEWPORT: Unsupported. Need to recreate all swap chains!
     ImGui_ImplVulkan_InitInfo* v = &g_VulkanInitInfo;
     VkResult err = vkDeviceWaitIdle(v->Device);
     check_vk_result(err);
-    ImGui_ImplVulkanH_DestroyWindowRenderBuffers(v->Device, &g_MainWindowRenderBuffers, v->Allocator);
+    ImGui_ImplVulkanH_DestroyAllViewportsRenderBuffers(v->Device, v->Allocator);
+
     g_VulkanInitInfo.MinImageCount = min_image_count;
 }
 
@@ -1248,6 +1285,7 @@ void ImGui_ImplVulkanH_CreateOrResizeWindow(VkInstance instance, VkPhysicalDevic
 {
     (void)instance;
     ImGui_ImplVulkanH_CreateWindowSwapChain(physical_device, device, wd, allocator, width, height, min_image_count);
+    //ImGui_ImplVulkan_CreatePipeline(device, allocator, VK_NULL_HANDLE, wd->RenderPass, VK_SAMPLE_COUNT_1_BIT, &wd->Pipeline, g_VulkanInitInfo.Subpass);
     ImGui_ImplVulkanH_CreateWindowCommandBuffers(physical_device, device, wd, queue_family, allocator);
 }
 
@@ -1312,3 +1350,193 @@ void ImGui_ImplVulkanH_DestroyWindowRenderBuffers(VkDevice device, ImGui_ImplVul
     buffers->Index = 0;
     buffers->Count = 0;
 }
+
+void ImGui_ImplVulkanH_DestroyAllViewportsRenderBuffers(VkDevice device, const VkAllocationCallbacks* allocator)
+{
+    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
+    for (int n = 0; n < platform_io.Viewports.Size; n++)
+        if (ImGuiViewportDataVulkan* data = (ImGuiViewportDataVulkan*)platform_io.Viewports[n]->RendererUserData)
+            ImGui_ImplVulkanH_DestroyWindowRenderBuffers(device, &data->RenderBuffers, allocator);
+}
+
+//--------------------------------------------------------------------------------------------------------
+// MULTI-VIEWPORT / PLATFORM INTERFACE SUPPORT
+// This is an _advanced_ and _optional_ feature, allowing the backend to create and handle multiple viewports simultaneously.
+// If you are new to dear imgui or creating a new binding for dear imgui, it is recommended that you completely ignore this section first..
+//--------------------------------------------------------------------------------------------------------
+
+static void ImGui_ImplVulkan_CreateWindow(ImGuiViewport* viewport)
+{
+    ImGuiViewportDataVulkan* data = IM_NEW(ImGuiViewportDataVulkan)();
+    viewport->RendererUserData = data;
+    ImGui_ImplVulkanH_Window* wd = &data->Window;
+    ImGui_ImplVulkan_InitInfo* v = &g_VulkanInitInfo;
+
+    // Create surface
+    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
+    VkResult err = (VkResult)platform_io.Platform_CreateVkSurface(viewport, (ImU64)v->Instance, (const void*)v->Allocator, (ImU64*)&wd->Surface);
+    check_vk_result(err);
+
+    // Check for WSI support
+    VkBool32 res;
+    vkGetPhysicalDeviceSurfaceSupportKHR(v->PhysicalDevice, v->QueueFamily, wd->Surface, &res);
+    if (res != VK_TRUE)
+    {
+        IM_ASSERT(0); // Error: no WSI support on physical device
+        return;
+    }
+
+    // Select Surface Format
+    const VkFormat requestSurfaceImageFormat[] = { VK_FORMAT_B8G8R8A8_UNORM, VK_FORMAT_R8G8B8A8_UNORM, VK_FORMAT_B8G8R8_UNORM, VK_FORMAT_R8G8B8_UNORM };
+    const VkColorSpaceKHR requestSurfaceColorSpace = VK_COLORSPACE_SRGB_NONLINEAR_KHR;
+    wd->SurfaceFormat = ImGui_ImplVulkanH_SelectSurfaceFormat(v->PhysicalDevice, wd->Surface, requestSurfaceImageFormat, (size_t)IM_ARRAYSIZE(requestSurfaceImageFormat), requestSurfaceColorSpace);
+
+    // Select Present Mode
+    // FIXME-VULKAN: Even thought mailbox seems to get us maximum framerate with a single window, it halves framerate with a second window etc. (w/ Nvidia and SDK 1.82.1)
+    VkPresentModeKHR present_modes[] = { VK_PRESENT_MODE_MAILBOX_KHR, VK_PRESENT_MODE_IMMEDIATE_KHR, VK_PRESENT_MODE_FIFO_KHR };
+    wd->PresentMode = ImGui_ImplVulkanH_SelectPresentMode(v->PhysicalDevice, wd->Surface, &present_modes[0], IM_ARRAYSIZE(present_modes));
+    //printf("[vulkan] Secondary window selected PresentMode = %d\n", wd->PresentMode);
+
+    // Create SwapChain, RenderPass, Framebuffer, etc.
+    wd->ClearEnable = (viewport->Flags & ImGuiViewportFlags_NoRendererClear) ? false : true;
+    ImGui_ImplVulkanH_CreateOrResizeWindow(v->Instance, v->PhysicalDevice, v->Device, wd, v->QueueFamily, v->Allocator, (int)viewport->Size.x, (int)viewport->Size.y, v->MinImageCount);
+    data->WindowOwned = true;
+}
+
+static void ImGui_ImplVulkan_DestroyWindow(ImGuiViewport* viewport)
+{
+    // The main viewport (owned by the application) will always have RendererUserData == NULL since we didn't create the data for it.
+    if (ImGuiViewportDataVulkan* data = (ImGuiViewportDataVulkan*)viewport->RendererUserData)
+    {
+        ImGui_ImplVulkan_InitInfo* v = &g_VulkanInitInfo;
+        if (data->WindowOwned)
+            ImGui_ImplVulkanH_DestroyWindow(v->Instance, v->Device, &data->Window, v->Allocator);
+        ImGui_ImplVulkanH_DestroyWindowRenderBuffers(v->Device, &data->RenderBuffers, v->Allocator);
+        IM_DELETE(data);
+    }
+    viewport->RendererUserData = NULL;
+}
+
+static void ImGui_ImplVulkan_SetWindowSize(ImGuiViewport* viewport, ImVec2 size)
+{
+    ImGuiViewportDataVulkan* data = (ImGuiViewportDataVulkan*)viewport->RendererUserData;
+    if (data == NULL) // This is NULL for the main viewport (which is left to the user/app to handle)
+        return;
+    ImGui_ImplVulkan_InitInfo* v = &g_VulkanInitInfo;
+    data->Window.ClearEnable = (viewport->Flags & ImGuiViewportFlags_NoRendererClear) ? false : true;
+    ImGui_ImplVulkanH_CreateOrResizeWindow(v->Instance, v->PhysicalDevice, v->Device, &data->Window, v->QueueFamily, v->Allocator, (int)size.x, (int)size.y, v->MinImageCount);
+}
+
+static void ImGui_ImplVulkan_RenderWindow(ImGuiViewport* viewport, void*)
+{
+    ImGuiViewportDataVulkan* data = (ImGuiViewportDataVulkan*)viewport->RendererUserData;
+    ImGui_ImplVulkanH_Window* wd = &data->Window;
+    ImGui_ImplVulkan_InitInfo* v = &g_VulkanInitInfo;
+    VkResult err;
+
+    ImGui_ImplVulkanH_Frame* fd = &wd->Frames[wd->FrameIndex];
+    ImGui_ImplVulkanH_FrameSemaphores* fsd = &wd->FrameSemaphores[wd->SemaphoreIndex];
+    {
+        for (;;)
+        {
+            err = vkWaitForFences(v->Device, 1, &fd->Fence, VK_TRUE, 100);
+            if (err == VK_SUCCESS) break;
+            if (err == VK_TIMEOUT) continue;
+            check_vk_result(err);
+        }
+        {
+            err = vkAcquireNextImageKHR(v->Device, wd->Swapchain, UINT64_MAX, fsd->ImageAcquiredSemaphore, VK_NULL_HANDLE, &wd->FrameIndex);
+            check_vk_result(err);
+            fd = &wd->Frames[wd->FrameIndex];
+        }
+        {
+            err = vkResetCommandPool(v->Device, fd->CommandPool, 0);
+            check_vk_result(err);
+            VkCommandBufferBeginInfo info = {};
+            info.sType = VK_STRUCTURE_TYPE_COMMAND_BUFFER_BEGIN_INFO;
+            info.flags |= VK_COMMAND_BUFFER_USAGE_ONE_TIME_SUBMIT_BIT;
+            err = vkBeginCommandBuffer(fd->CommandBuffer, &info);
+            check_vk_result(err);
+        }
+        {
+            ImVec4 clear_color = ImVec4(0.0f, 0.0f, 0.0f, 1.0f);
+            memcpy(&wd->ClearValue.color.float32[0], &clear_color, 4 * sizeof(float));
+
+            VkRenderPassBeginInfo info = {};
+            info.sType = VK_STRUCTURE_TYPE_RENDER_PASS_BEGIN_INFO;
+            info.renderPass = wd->RenderPass;
+            info.framebuffer = fd->Framebuffer;
+            info.renderArea.extent.width = wd->Width;
+            info.renderArea.extent.height = wd->Height;
+            info.clearValueCount = (viewport->Flags & ImGuiViewportFlags_NoRendererClear) ? 0 : 1;
+            info.pClearValues = (viewport->Flags & ImGuiViewportFlags_NoRendererClear) ? NULL : &wd->ClearValue;
+            vkCmdBeginRenderPass(fd->CommandBuffer, &info, VK_SUBPASS_CONTENTS_INLINE);
+        }
+    }
+
+    ImGui_ImplVulkan_RenderDrawData(viewport->DrawData, fd->CommandBuffer, wd->Pipeline);
+
+    {
+        vkCmdEndRenderPass(fd->CommandBuffer);
+        {
+            VkPipelineStageFlags wait_stage = VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT;
+            VkSubmitInfo info = {};
+            info.sType = VK_STRUCTURE_TYPE_SUBMIT_INFO;
+            info.waitSemaphoreCount = 1;
+            info.pWaitSemaphores = &fsd->ImageAcquiredSemaphore;
+            info.pWaitDstStageMask = &wait_stage;
+            info.commandBufferCount = 1;
+            info.pCommandBuffers = &fd->CommandBuffer;
+            info.signalSemaphoreCount = 1;
+            info.pSignalSemaphores = &fsd->RenderCompleteSemaphore;
+
+            err = vkEndCommandBuffer(fd->CommandBuffer);
+            check_vk_result(err);
+            err = vkResetFences(v->Device, 1, &fd->Fence);
+            check_vk_result(err);
+            err = vkQueueSubmit(v->Queue, 1, &info, fd->Fence);
+            check_vk_result(err);
+        }
+    }
+}
+
+static void ImGui_ImplVulkan_SwapBuffers(ImGuiViewport* viewport, void*)
+{
+    ImGuiViewportDataVulkan* data = (ImGuiViewportDataVulkan*)viewport->RendererUserData;
+    ImGui_ImplVulkanH_Window* wd = &data->Window;
+    ImGui_ImplVulkan_InitInfo* v = &g_VulkanInitInfo;
+
+    VkResult err;
+    uint32_t present_index = wd->FrameIndex;
+
+    ImGui_ImplVulkanH_FrameSemaphores* fsd = &wd->FrameSemaphores[wd->SemaphoreIndex];
+    VkPresentInfoKHR info = {};
+    info.sType = VK_STRUCTURE_TYPE_PRESENT_INFO_KHR;
+    info.waitSemaphoreCount = 1;
+    info.pWaitSemaphores = &fsd->RenderCompleteSemaphore;
+    info.swapchainCount = 1;
+    info.pSwapchains = &wd->Swapchain;
+    info.pImageIndices = &present_index;
+    err = vkQueuePresentKHR(v->Queue, &info);
+    check_vk_result(err);
+
+    wd->FrameIndex = (wd->FrameIndex + 1) % wd->ImageCount;         // This is for the next vkWaitForFences()
+    wd->SemaphoreIndex = (wd->SemaphoreIndex + 1) % wd->ImageCount; // Now we can use the next set of semaphores
+}
+
+void ImGui_ImplVulkan_InitPlatformInterface()
+{
+    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
+    if (ImGui::GetIO().ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+        IM_ASSERT(platform_io.Platform_CreateVkSurface != NULL && "Platform needs to setup the CreateVkSurface handler.");
+    platform_io.Renderer_CreateWindow = ImGui_ImplVulkan_CreateWindow;
+    platform_io.Renderer_DestroyWindow = ImGui_ImplVulkan_DestroyWindow;
+    platform_io.Renderer_SetWindowSize = ImGui_ImplVulkan_SetWindowSize;
+    platform_io.Renderer_RenderWindow = ImGui_ImplVulkan_RenderWindow;
+    platform_io.Renderer_SwapBuffers = ImGui_ImplVulkan_SwapBuffers;
+}
+
+void ImGui_ImplVulkan_ShutdownPlatformInterface()
+{
+    ImGui::DestroyPlatformWindows();
+}

backends/imgui_impl_vulkan.h

@@ -4,6 +4,7 @@
 // Implemented features:
 //  [X] Renderer: Support for large meshes (64k+ vertices) with 16-bit indices.
 // Missing features:
+//  [ ] Platform: Multi-viewport / platform windows.
 //  [ ] Renderer: User texture binding. Changes of ImTextureID aren't supported by this backend! See https://github.com/ocornut/imgui/pull/914
 
 // You can copy and use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
@@ -60,8 +61,8 @@ IMGUI_IMPL_API void     ImGui_ImplVulkan_SetMinImageCount(uint32_t min_image_cou
 // You probably do NOT need to use or care about those functions.
 // Those functions only exist because:
 //   1) they facilitate the readability and maintenance of the multiple main.cpp examples files.
-//   2) the upcoming multi-viewport feature will need them internally.
-// Generally we avoid exposing any kind of superfluous high-level helpers in the backends,
+//   2) the multi-viewport / platform window implementation needs them internally.
+// Generally we avoid exposing any kind of superfluous high-level helpers in the bindings,
 // but it is too much code to duplicate everywhere so we exceptionally expose them.
 //
 // Your engine/app will likely _already_ have code to setup all that stuff (swap chain, render pass, frame buffers, etc.).

backends/imgui_impl_win32.cpp

@@ -6,6 +6,7 @@
 //  [X] Platform: Mouse cursor shape and visibility. Disable with 'io.ConfigFlags |= ImGuiConfigFlags_NoMouseCursorChange'.
 //  [X] Platform: Keyboard arrays indexed using VK_* Virtual Key Codes, e.g. ImGui::IsKeyPressed(VK_SPACE).
 //  [X] Platform: Gamepad support. Enabled with 'io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad'.
+//  [X] Platform: Multi-viewport support (multiple windows). Enable with 'io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable'.
 
 // You can copy and use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
 // If you are new to Dear ImGui, read documentation from the docs/ folder + read the top of imgui.cpp.
@@ -32,6 +33,7 @@
 
 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
+//  2020-XX-XX: Platform: Added support for multiple windows via the ImGuiPlatformIO interface.
 //  2020-12-04: Misc: Fixed setting of io.DisplaySize to invalid/uninitialized data when after hwnd has been closed.
 //  2020-03-03: Inputs: Calling AddInputCharacterUTF16() to support surrogate pairs leading to codepoint >= 0x10000 (for more complete CJK inputs)
 //  2020-02-17: Added ImGui_ImplWin32_EnableDpiAwareness(), ImGui_ImplWin32_GetDpiScaleForHwnd(), ImGui_ImplWin32_GetDpiScaleForMonitor() helper functions.
@@ -64,6 +66,12 @@ static INT64                g_TicksPerSecond = 0;
 static ImGuiMouseCursor     g_LastMouseCursor = ImGuiMouseCursor_COUNT;
 static bool                 g_HasGamepad = false;
 static bool                 g_WantUpdateHasGamepad = true;
+static bool                 g_WantUpdateMonitors = true;
+
+// Forward Declarations
+static void ImGui_ImplWin32_InitPlatformInterface();
+static void ImGui_ImplWin32_ShutdownPlatformInterface();
+static void ImGui_ImplWin32_UpdateMonitors();
 
 // Functions
 bool    ImGui_ImplWin32_Init(void* hwnd)
@@ -74,12 +82,19 @@ bool    ImGui_ImplWin32_Init(void* hwnd)
         return false;
 
     // Setup backend capabilities flags
-    g_hWnd = (HWND)hwnd;
     ImGuiIO& io = ImGui::GetIO();
     io.BackendFlags |= ImGuiBackendFlags_HasMouseCursors;         // We can honor GetMouseCursor() values (optional)
     io.BackendFlags |= ImGuiBackendFlags_HasSetMousePos;          // We can honor io.WantSetMousePos requests (optional, rarely used)
+    io.BackendFlags |= ImGuiBackendFlags_PlatformHasViewports;    // We can create multi-viewports on the Platform side (optional)
+    io.BackendFlags |= ImGuiBackendFlags_HasMouseHoveredViewport; // We can set io.MouseHoveredViewport correctly (optional, not easy)
     io.BackendPlatformName = "imgui_impl_win32";
-    io.ImeWindowHandle = hwnd;
+
+    // Our mouse update function expect PlatformHandle to be filled for the main viewport
+    g_hWnd = (HWND)hwnd;
+    ImGuiViewport* main_viewport = ImGui::GetMainViewport();
+    main_viewport->PlatformHandle = main_viewport->PlatformHandleRaw = (void*)g_hWnd;
+    if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+        ImGui_ImplWin32_InitPlatformInterface();
 
     // Keyboard mapping. ImGui will use those indices to peek into the io.KeysDown[] array that we will update during the application lifetime.
     io.KeyMap[ImGuiKey_Tab] = VK_TAB;
@@ -110,6 +125,7 @@ bool    ImGui_ImplWin32_Init(void* hwnd)
 
 void    ImGui_ImplWin32_Shutdown()
 {
+    ImGui_ImplWin32_ShutdownPlatformInterface();
     g_hWnd = (HWND)0;
 }
 
@@ -146,25 +162,63 @@ static bool ImGui_ImplWin32_UpdateMouseCursor()
     return true;
 }
 
+// This code supports multi-viewports (multiple OS Windows mapped into different Dear ImGui viewports)
+// Because of that, it is a little more complicated than your typical single-viewport binding code!
 static void ImGui_ImplWin32_UpdateMousePos()
 {
     ImGuiIO& io = ImGui::GetIO();
 
     // Set OS mouse position if requested (rarely used, only when ImGuiConfigFlags_NavEnableSetMousePos is enabled by user)
+    // (When multi-viewports are enabled, all imgui positions are same as OS positions)
     if (io.WantSetMousePos)
     {
         POINT pos = { (int)io.MousePos.x, (int)io.MousePos.y };
-        if (::ClientToScreen(g_hWnd, &pos))
+        if ((io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable) != 0 || ::ClientToScreen(g_hWnd, &pos))
+            ::ClientToScreen(g_hWnd, &pos);
         ::SetCursorPos(pos.x, pos.y);
     }
 
-    // Set mouse position
     io.MousePos = ImVec2(-FLT_MAX, -FLT_MAX);
-    POINT pos;
-    if (HWND active_window = ::GetForegroundWindow())
-        if (active_window == g_hWnd || ::IsChild(active_window, g_hWnd))
-            if (::GetCursorPos(&pos) && ::ScreenToClient(g_hWnd, &pos))
-                io.MousePos = ImVec2((float)pos.x, (float)pos.y);
+    io.MouseHoveredViewport = 0;
+
+    // Set imgui mouse position
+    POINT mouse_screen_pos;
+    if (!::GetCursorPos(&mouse_screen_pos))
+        return;
+    if (HWND focused_hwnd = ::GetForegroundWindow())
+    {
+        if (::IsChild(focused_hwnd, g_hWnd))
+            focused_hwnd = g_hWnd;
+        if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+        {
+            // Multi-viewport mode: mouse position in OS absolute coordinates (io.MousePos is (0,0) when the mouse is on the upper-left of the primary monitor)
+            // This is the position you can get with GetCursorPos(). In theory adding viewport->Pos is also the reverse operation of doing ScreenToClient().
+            if (ImGui::FindViewportByPlatformHandle((void*)focused_hwnd) != NULL)
+                io.MousePos = ImVec2((float)mouse_screen_pos.x, (float)mouse_screen_pos.y);
+        }
+        else
+        {
+            // Single viewport mode: mouse position in client window coordinates (io.MousePos is (0,0) when the mouse is on the upper-left corner of the app window.)
+            // This is the position you can get with GetCursorPos() + ScreenToClient() or from WM_MOUSEMOVE.
+            if (focused_hwnd == g_hWnd)
+            {
+                POINT mouse_client_pos = mouse_screen_pos;
+                ::ScreenToClient(focused_hwnd, &mouse_client_pos);
+                io.MousePos = ImVec2((float)mouse_client_pos.x, (float)mouse_client_pos.y);
+            }
+        }
+    }
+
+    // (Optional) When using multiple viewports: set io.MouseHoveredViewport to the viewport the OS mouse cursor is hovering.
+    // Important: this information is not easy to provide and many high-level windowing library won't be able to provide it correctly, because
+    // - This is _ignoring_ viewports with the ImGuiViewportFlags_NoInputs flag (pass-through windows).
+    // - This is _regardless_ of whether another viewport is focused or being dragged from.
+    // If ImGuiBackendFlags_HasMouseHoveredViewport is not set by the backend, imgui will ignore this field and infer the information by relying on the
+    // rectangles and last focused time of every viewports it knows about. It will be unaware of foreign windows that may be sitting between or over your windows.
+    if (HWND hovered_hwnd = ::WindowFromPoint(mouse_screen_pos))
+        if (ImGuiViewport* viewport = ImGui::FindViewportByPlatformHandle((void*)hovered_hwnd))
+            if ((viewport->Flags & ImGuiViewportFlags_NoInputs) == 0) // FIXME: We still get our NoInputs window with WM_NCHITTEST/HTTRANSPARENT code when decorated?
+                io.MouseHoveredViewport = viewport->ID;
 }
 
 // Gamepad navigation mapping
@@ -216,6 +270,33 @@ static void ImGui_ImplWin32_UpdateGamepads()
 #endif // #ifndef IMGUI_IMPL_WIN32_DISABLE_GAMEPAD
 }
 
+static BOOL CALLBACK ImGui_ImplWin32_UpdateMonitors_EnumFunc(HMONITOR monitor, HDC, LPRECT, LPARAM)
+{
+    MONITORINFO info = { 0 };
+    info.cbSize = sizeof(MONITORINFO);
+    if (!::GetMonitorInfo(monitor, &info))
+        return TRUE;
+    ImGuiPlatformMonitor imgui_monitor;
+    imgui_monitor.MainPos = ImVec2((float)info.rcMonitor.left, (float)info.rcMonitor.top);
+    imgui_monitor.MainSize = ImVec2((float)(info.rcMonitor.right - info.rcMonitor.left), (float)(info.rcMonitor.bottom - info.rcMonitor.top));
+    imgui_monitor.WorkPos = ImVec2((float)info.rcWork.left, (float)info.rcWork.top);
+    imgui_monitor.WorkSize = ImVec2((float)(info.rcWork.right - info.rcWork.left), (float)(info.rcWork.bottom - info.rcWork.top));
+    imgui_monitor.DpiScale = ImGui_ImplWin32_GetDpiScaleForMonitor(monitor);
+    ImGuiPlatformIO& io = ImGui::GetPlatformIO();
+    if (info.dwFlags & MONITORINFOF_PRIMARY)
+        io.Monitors.push_front(imgui_monitor);
+    else
+        io.Monitors.push_back(imgui_monitor);
+    return TRUE;
+}
+
+static void ImGui_ImplWin32_UpdateMonitors()
+{
+    ImGui::GetPlatformIO().Monitors.resize(0);
+    ::EnumDisplayMonitors(NULL, NULL, ImGui_ImplWin32_UpdateMonitors_EnumFunc, NULL);
+    g_WantUpdateMonitors = false;
+}
+
 void    ImGui_ImplWin32_NewFrame()
 {
     ImGuiIO& io = ImGui::GetIO();
@@ -225,6 +306,8 @@ void    ImGui_ImplWin32_NewFrame()
     RECT rect = { 0, 0, 0, 0 };
     ::GetClientRect(g_hWnd, &rect);
     io.DisplaySize = ImVec2((float)(rect.right - rect.left), (float)(rect.bottom - rect.top));
+    if (g_WantUpdateMonitors)
+        ImGui_ImplWin32_UpdateMonitors();
 
     // Setup time step
     INT64 current_time = 0;
@@ -341,6 +424,9 @@ IMGUI_IMPL_API LRESULT ImGui_ImplWin32_WndProcHandler(HWND hwnd, UINT msg, WPARA
         if ((UINT)wParam == DBT_DEVNODES_CHANGED)
             g_WantUpdateHasGamepad = true;
         return 0;
+    case WM_DISPLAYCHANGE:
+        g_WantUpdateMonitors = true;
+        return 0;
     }
     return 0;
 }
@@ -392,6 +478,9 @@ typedef DPI_AWARENESS_CONTEXT(WINAPI* PFN_SetThreadDpiAwarenessContext)(DPI_AWAR
 // Helper function to enable DPI awareness without setting up a manifest
 void ImGui_ImplWin32_EnableDpiAwareness()
 {
+    // Make sure monitors will be updated with latest correct scaling
+    g_WantUpdateMonitors = true;
+
     // if (IsWindows10OrGreater()) // This needs a manifest to succeed. Instead we try to grab the function pointer!
     {
         static HINSTANCE user32_dll = ::LoadLibraryA("user32.dll"); // Reference counted per-process
@@ -448,4 +537,353 @@ float ImGui_ImplWin32_GetDpiScaleForHwnd(void* hwnd)
     return ImGui_ImplWin32_GetDpiScaleForMonitor(monitor);
 }
 
+
+//--------------------------------------------------------------------------------------------------------
+// IME (Input Method Editor) basic support for e.g. Asian language users
+//--------------------------------------------------------------------------------------------------------
+
+#if defined(WINAPI_FAMILY) && (WINAPI_FAMILY == WINAPI_FAMILY_APP) // UWP doesn't have Win32 functions
+#define IMGUI_DISABLE_WIN32_DEFAULT_IME_FUNCTIONS
+#endif
+
+#if defined(_WIN32) && !defined(IMGUI_DISABLE_WIN32_FUNCTIONS) && !defined(IMGUI_DISABLE_WIN32_DEFAULT_IME_FUNCTIONS) && !defined(__GNUC__)
+#define HAS_WIN32_IME   1
+#include <imm.h>
+#ifdef _MSC_VER
+#pragma comment(lib, "imm32")
+#endif
+static void ImGui_ImplWin32_SetImeInputPos(ImGuiViewport* viewport, ImVec2 pos)
+{
+    COMPOSITIONFORM cf = { CFS_FORCE_POSITION,{ (LONG)(pos.x - viewport->Pos.x), (LONG)(pos.y - viewport->Pos.y) },{ 0, 0, 0, 0 } };
+    if (HWND hwnd = (HWND)viewport->PlatformHandle)
+        if (HIMC himc = ::ImmGetContext(hwnd))
+        {
+            ::ImmSetCompositionWindow(himc, &cf);
+            ::ImmReleaseContext(hwnd, himc);
+        }
+}
+#else
+#define HAS_WIN32_IME   0
+#endif
+
+//--------------------------------------------------------------------------------------------------------
+// MULTI-VIEWPORT / PLATFORM INTERFACE SUPPORT
+// This is an _advanced_ and _optional_ feature, allowing the backend to create and handle multiple viewports simultaneously.
+// If you are new to dear imgui or creating a new binding for dear imgui, it is recommended that you completely ignore this section first..
+//--------------------------------------------------------------------------------------------------------
+
+// Helper structure we store in the void* RenderUserData field of each ImGuiViewport to easily retrieve our backend data.
+struct ImGuiViewportDataWin32
+{
+    HWND    Hwnd;
+    bool    HwndOwned;
+    DWORD   DwStyle;
+    DWORD   DwExStyle;
+
+    ImGuiViewportDataWin32() { Hwnd = NULL; HwndOwned = false;  DwStyle = DwExStyle = 0; }
+    ~ImGuiViewportDataWin32() { IM_ASSERT(Hwnd == NULL); }
+};
+
+static void ImGui_ImplWin32_GetWin32StyleFromViewportFlags(ImGuiViewportFlags flags, DWORD* out_style, DWORD* out_ex_style)
+{
+    if (flags & ImGuiViewportFlags_NoDecoration)
+        *out_style = WS_POPUP;
+    else
+        *out_style = WS_OVERLAPPEDWINDOW;
+
+    if (flags & ImGuiViewportFlags_NoTaskBarIcon)
+        *out_ex_style = WS_EX_TOOLWINDOW;
+    else
+        *out_ex_style = WS_EX_APPWINDOW;
+
+    if (flags & ImGuiViewportFlags_TopMost)
+        *out_ex_style |= WS_EX_TOPMOST;
+}
+
+static void ImGui_ImplWin32_CreateWindow(ImGuiViewport* viewport)
+{
+    ImGuiViewportDataWin32* data = IM_NEW(ImGuiViewportDataWin32)();
+    viewport->PlatformUserData = data;
+
+    // Select style and parent window
+    ImGui_ImplWin32_GetWin32StyleFromViewportFlags(viewport->Flags, &data->DwStyle, &data->DwExStyle);
+    HWND parent_window = NULL;
+    if (viewport->ParentViewportId != 0)
+        if (ImGuiViewport* parent_viewport = ImGui::FindViewportByID(viewport->ParentViewportId))
+            parent_window = (HWND)parent_viewport->PlatformHandle;
+
+    // Create window
+    RECT rect = { (LONG)viewport->Pos.x, (LONG)viewport->Pos.y, (LONG)(viewport->Pos.x + viewport->Size.x), (LONG)(viewport->Pos.y + viewport->Size.y) };
+    ::AdjustWindowRectEx(&rect, data->DwStyle, FALSE, data->DwExStyle);
+    data->Hwnd = ::CreateWindowEx(
+        data->DwExStyle, _T("ImGui Platform"), _T("Untitled"), data->DwStyle,   // Style, class name, window name
+        rect.left, rect.top, rect.right - rect.left, rect.bottom - rect.top,    // Window area
+        parent_window, NULL, ::GetModuleHandle(NULL), NULL);                    // Parent window, Menu, Instance, Param
+    data->HwndOwned = true;
+    viewport->PlatformRequestResize = false;
+    viewport->PlatformHandle = viewport->PlatformHandleRaw = data->Hwnd;
+}
+
+static void ImGui_ImplWin32_DestroyWindow(ImGuiViewport* viewport)
+{
+    if (ImGuiViewportDataWin32* data = (ImGuiViewportDataWin32*)viewport->PlatformUserData)
+    {
+        if (::GetCapture() == data->Hwnd)
+        {
+            // Transfer capture so if we started dragging from a window that later disappears, we'll still receive the MOUSEUP event.
+            ::ReleaseCapture();
+            ::SetCapture(g_hWnd);
+        }
+        if (data->Hwnd && data->HwndOwned)
+            ::DestroyWindow(data->Hwnd);
+        data->Hwnd = NULL;
+        IM_DELETE(data);
+    }
+    viewport->PlatformUserData = viewport->PlatformHandle = NULL;
+}
+
+static void ImGui_ImplWin32_ShowWindow(ImGuiViewport* viewport)
+{
+    ImGuiViewportDataWin32* data = (ImGuiViewportDataWin32*)viewport->PlatformUserData;
+    IM_ASSERT(data->Hwnd != 0);
+    if (viewport->Flags & ImGuiViewportFlags_NoFocusOnAppearing)
+        ::ShowWindow(data->Hwnd, SW_SHOWNA);
+    else
+        ::ShowWindow(data->Hwnd, SW_SHOW);
+}
+
+static void ImGui_ImplWin32_UpdateWindow(ImGuiViewport* viewport)
+{
+    // (Optional) Update Win32 style if it changed _after_ creation.
+    // Generally they won't change unless configuration flags are changed, but advanced uses (such as manually rewriting viewport flags) make this useful.
+    ImGuiViewportDataWin32* data = (ImGuiViewportDataWin32*)viewport->PlatformUserData;
+    IM_ASSERT(data->Hwnd != 0);
+    DWORD new_style;
+    DWORD new_ex_style;
+    ImGui_ImplWin32_GetWin32StyleFromViewportFlags(viewport->Flags, &new_style, &new_ex_style);
+
+    // Only reapply the flags that have been changed from our point of view (as other flags are being modified by Windows)
+    if (data->DwStyle != new_style || data->DwExStyle != new_ex_style)
+    {
+        // (Optional) Update TopMost state if it changed _after_ creation
+        bool top_most_changed = (data->DwExStyle & WS_EX_TOPMOST) != (new_ex_style & WS_EX_TOPMOST);
+        HWND insert_after = top_most_changed ? ((viewport->Flags & ImGuiViewportFlags_TopMost) ? HWND_TOPMOST : HWND_NOTOPMOST) : 0;
+        UINT swp_flag = top_most_changed ? 0 : SWP_NOZORDER;
+
+        // Apply flags and position (since it is affected by flags)
+        data->DwStyle = new_style;
+        data->DwExStyle = new_ex_style;
+        ::SetWindowLong(data->Hwnd, GWL_STYLE, data->DwStyle);
+        ::SetWindowLong(data->Hwnd, GWL_EXSTYLE, data->DwExStyle);
+        RECT rect = { (LONG)viewport->Pos.x, (LONG)viewport->Pos.y, (LONG)(viewport->Pos.x + viewport->Size.x), (LONG)(viewport->Pos.y + viewport->Size.y) };
+        ::AdjustWindowRectEx(&rect, data->DwStyle, FALSE, data->DwExStyle); // Client to Screen
+        ::SetWindowPos(data->Hwnd, insert_after, rect.left, rect.top, rect.right - rect.left, rect.bottom - rect.top, swp_flag | SWP_NOACTIVATE | SWP_FRAMECHANGED);
+        ::ShowWindow(data->Hwnd, SW_SHOWNA); // This is necessary when we alter the style
+        viewport->PlatformRequestMove = viewport->PlatformRequestResize = true;
+    }
+}
+
+static ImVec2 ImGui_ImplWin32_GetWindowPos(ImGuiViewport* viewport)
+{
+    ImGuiViewportDataWin32* data = (ImGuiViewportDataWin32*)viewport->PlatformUserData;
+    IM_ASSERT(data->Hwnd != 0);
+    POINT pos = { 0, 0 };
+    ::ClientToScreen(data->Hwnd, &pos);
+    return ImVec2((float)pos.x, (float)pos.y);
+}
+
+static void ImGui_ImplWin32_SetWindowPos(ImGuiViewport* viewport, ImVec2 pos)
+{
+    ImGuiViewportDataWin32* data = (ImGuiViewportDataWin32*)viewport->PlatformUserData;
+    IM_ASSERT(data->Hwnd != 0);
+    RECT rect = { (LONG)pos.x, (LONG)pos.y, (LONG)pos.x, (LONG)pos.y };
+    ::AdjustWindowRectEx(&rect, data->DwStyle, FALSE, data->DwExStyle);
+    ::SetWindowPos(data->Hwnd, NULL, rect.left, rect.top, 0, 0, SWP_NOZORDER | SWP_NOSIZE | SWP_NOACTIVATE);
+}
+
+static ImVec2 ImGui_ImplWin32_GetWindowSize(ImGuiViewport* viewport)
+{
+    ImGuiViewportDataWin32* data = (ImGuiViewportDataWin32*)viewport->PlatformUserData;
+    IM_ASSERT(data->Hwnd != 0);
+    RECT rect;
+    ::GetClientRect(data->Hwnd, &rect);
+    return ImVec2(float(rect.right - rect.left), float(rect.bottom - rect.top));
+}
+
+static void ImGui_ImplWin32_SetWindowSize(ImGuiViewport* viewport, ImVec2 size)
+{
+    ImGuiViewportDataWin32* data = (ImGuiViewportDataWin32*)viewport->PlatformUserData;
+    IM_ASSERT(data->Hwnd != 0);
+    RECT rect = { 0, 0, (LONG)size.x, (LONG)size.y };
+    ::AdjustWindowRectEx(&rect, data->DwStyle, FALSE, data->DwExStyle); // Client to Screen
+    ::SetWindowPos(data->Hwnd, NULL, 0, 0, rect.right - rect.left, rect.bottom - rect.top, SWP_NOZORDER | SWP_NOMOVE | SWP_NOACTIVATE);
+}
+
+static void ImGui_ImplWin32_SetWindowFocus(ImGuiViewport* viewport)
+{
+    ImGuiViewportDataWin32* data = (ImGuiViewportDataWin32*)viewport->PlatformUserData;
+    IM_ASSERT(data->Hwnd != 0);
+    ::BringWindowToTop(data->Hwnd);
+    ::SetForegroundWindow(data->Hwnd);
+    ::SetFocus(data->Hwnd);
+}
+
+static bool ImGui_ImplWin32_GetWindowFocus(ImGuiViewport* viewport)
+{
+    ImGuiViewportDataWin32* data = (ImGuiViewportDataWin32*)viewport->PlatformUserData;
+    IM_ASSERT(data->Hwnd != 0);
+    return ::GetForegroundWindow() == data->Hwnd;
+}
+
+static bool ImGui_ImplWin32_GetWindowMinimized(ImGuiViewport* viewport)
+{
+    ImGuiViewportDataWin32* data = (ImGuiViewportDataWin32*)viewport->PlatformUserData;
+    IM_ASSERT(data->Hwnd != 0);
+    return ::IsIconic(data->Hwnd) != 0;
+}
+
+static void ImGui_ImplWin32_SetWindowTitle(ImGuiViewport* viewport, const char* title)
+{
+    // ::SetWindowTextA() doesn't properly handle UTF-8 so we explicitely convert our string.
+    ImGuiViewportDataWin32* data = (ImGuiViewportDataWin32*)viewport->PlatformUserData;
+    IM_ASSERT(data->Hwnd != 0);
+    int n = ::MultiByteToWideChar(CP_UTF8, 0, title, -1, NULL, 0);
+    ImVector<wchar_t> title_w;
+    title_w.resize(n);
+    ::MultiByteToWideChar(CP_UTF8, 0, title, -1, title_w.Data, n);
+    ::SetWindowTextW(data->Hwnd, title_w.Data);
+}
+
+static void ImGui_ImplWin32_SetWindowAlpha(ImGuiViewport* viewport, float alpha)
+{
+    ImGuiViewportDataWin32* data = (ImGuiViewportDataWin32*)viewport->PlatformUserData;
+    IM_ASSERT(data->Hwnd != 0);
+    IM_ASSERT(alpha >= 0.0f && alpha <= 1.0f);
+    if (alpha < 1.0f)
+    {
+        DWORD style = ::GetWindowLongW(data->Hwnd, GWL_EXSTYLE) | WS_EX_LAYERED;
+        ::SetWindowLongW(data->Hwnd, GWL_EXSTYLE, style);
+        ::SetLayeredWindowAttributes(data->Hwnd, 0, (BYTE)(255 * alpha), LWA_ALPHA);
+    }
+    else
+    {
+        DWORD style = ::GetWindowLongW(data->Hwnd, GWL_EXSTYLE) & ~WS_EX_LAYERED;
+        ::SetWindowLongW(data->Hwnd, GWL_EXSTYLE, style);
+    }
+}
+
+static float ImGui_ImplWin32_GetWindowDpiScale(ImGuiViewport* viewport)
+{
+    ImGuiViewportDataWin32* data = (ImGuiViewportDataWin32*)viewport->PlatformUserData;
+    IM_ASSERT(data->Hwnd != 0);
+    return ImGui_ImplWin32_GetDpiScaleForHwnd(data->Hwnd);
+}
+
+// FIXME-DPI: Testing DPI related ideas
+static void ImGui_ImplWin32_OnChangedViewport(ImGuiViewport* viewport)
+{
+    (void)viewport;
+#if 0
+    ImGuiStyle default_style;
+    //default_style.WindowPadding = ImVec2(0, 0);
+    //default_style.WindowBorderSize = 0.0f;
+    //default_style.ItemSpacing.y = 3.0f;
+    //default_style.FramePadding = ImVec2(0, 0);
+    default_style.ScaleAllSizes(viewport->DpiScale);
+    ImGuiStyle& style = ImGui::GetStyle();
+    style = default_style;
+#endif
+}
+
+static LRESULT CALLBACK ImGui_ImplWin32_WndProcHandler_PlatformWindow(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam)
+{
+    if (ImGui_ImplWin32_WndProcHandler(hWnd, msg, wParam, lParam))
+        return true;
+
+    if (ImGuiViewport* viewport = ImGui::FindViewportByPlatformHandle((void*)hWnd))
+    {
+        switch (msg)
+        {
+        case WM_CLOSE:
+            viewport->PlatformRequestClose = true;
+            return 0;
+        case WM_MOVE:
+            viewport->PlatformRequestMove = true;
+            break;
+        case WM_SIZE:
+            viewport->PlatformRequestResize = true;
+            break;
+        case WM_MOUSEACTIVATE:
+            if (viewport->Flags & ImGuiViewportFlags_NoFocusOnClick)
+                return MA_NOACTIVATE;
+            break;
+        case WM_NCHITTEST:
+            // Let mouse pass-through the window. This will allow the backend to set io.MouseHoveredViewport properly (which is OPTIONAL).
+            // The ImGuiViewportFlags_NoInputs flag is set while dragging a viewport, as want to detect the window behind the one we are dragging.
+            // If you cannot easily access those viewport flags from your windowing/event code: you may manually synchronize its state e.g. in
+            // your main loop after calling UpdatePlatformWindows(). Iterate all viewports/platform windows and pass the flag to your windowing system.
+            if (viewport->Flags & ImGuiViewportFlags_NoInputs)
+                return HTTRANSPARENT;
+            break;
+        }
+    }
+
+    return DefWindowProc(hWnd, msg, wParam, lParam);
+}
+
+static void ImGui_ImplWin32_InitPlatformInterface()
+{
+    WNDCLASSEX wcex;
+    wcex.cbSize = sizeof(WNDCLASSEX);
+    wcex.style = CS_HREDRAW | CS_VREDRAW;
+    wcex.lpfnWndProc = ImGui_ImplWin32_WndProcHandler_PlatformWindow;
+    wcex.cbClsExtra = 0;
+    wcex.cbWndExtra = 0;
+    wcex.hInstance = ::GetModuleHandle(NULL);
+    wcex.hIcon = NULL;
+    wcex.hCursor = NULL;
+    wcex.hbrBackground = (HBRUSH)(COLOR_BACKGROUND + 1);
+    wcex.lpszMenuName = NULL;
+    wcex.lpszClassName = _T("ImGui Platform");
+    wcex.hIconSm = NULL;
+    ::RegisterClassEx(&wcex);
+
+    ImGui_ImplWin32_UpdateMonitors();
+
+    // Register platform interface (will be coupled with a renderer interface)
+    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
+    platform_io.Platform_CreateWindow = ImGui_ImplWin32_CreateWindow;
+    platform_io.Platform_DestroyWindow = ImGui_ImplWin32_DestroyWindow;
+    platform_io.Platform_ShowWindow = ImGui_ImplWin32_ShowWindow;
+    platform_io.Platform_SetWindowPos = ImGui_ImplWin32_SetWindowPos;
+    platform_io.Platform_GetWindowPos = ImGui_ImplWin32_GetWindowPos;
+    platform_io.Platform_SetWindowSize = ImGui_ImplWin32_SetWindowSize;
+    platform_io.Platform_GetWindowSize = ImGui_ImplWin32_GetWindowSize;
+    platform_io.Platform_SetWindowFocus = ImGui_ImplWin32_SetWindowFocus;
+    platform_io.Platform_GetWindowFocus = ImGui_ImplWin32_GetWindowFocus;
+    platform_io.Platform_GetWindowMinimized = ImGui_ImplWin32_GetWindowMinimized;
+    platform_io.Platform_SetWindowTitle = ImGui_ImplWin32_SetWindowTitle;
+    platform_io.Platform_SetWindowAlpha = ImGui_ImplWin32_SetWindowAlpha;
+    platform_io.Platform_UpdateWindow = ImGui_ImplWin32_UpdateWindow;
+    platform_io.Platform_GetWindowDpiScale = ImGui_ImplWin32_GetWindowDpiScale; // FIXME-DPI
+    platform_io.Platform_OnChangedViewport = ImGui_ImplWin32_OnChangedViewport; // FIXME-DPI
+#if HAS_WIN32_IME
+    platform_io.Platform_SetImeInputPos = ImGui_ImplWin32_SetImeInputPos;
+#endif
+
+    // Register main window handle (which is owned by the main application, not by us)
+    // This is mostly for simplicity and consistency, so that our code (e.g. mouse handling etc.) can use same logic for main and secondary viewports.
+    ImGuiViewport* main_viewport = ImGui::GetMainViewport();
+    ImGuiViewportDataWin32* data = IM_NEW(ImGuiViewportDataWin32)();
+    data->Hwnd = g_hWnd;
+    data->HwndOwned = false;
+    main_viewport->PlatformUserData = data;
+    main_viewport->PlatformHandle = (void*)g_hWnd;
+}
+
+static void ImGui_ImplWin32_ShutdownPlatformInterface()
+{
+    ::UnregisterClass(_T("ImGui Platform"), ::GetModuleHandle(NULL));
+}
+
 //---------------------------------------------------------------------------------------------------------

backends/imgui_impl_win32.h

@@ -6,6 +6,7 @@
 //  [X] Platform: Mouse cursor shape and visibility. Disable with 'io.ConfigFlags |= ImGuiConfigFlags_NoMouseCursorChange'.
 //  [X] Platform: Keyboard arrays indexed using VK_* Virtual Key Codes, e.g. ImGui::IsKeyPressed(VK_SPACE).
 //  [X] Platform: Gamepad support. Enabled with 'io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad'.
+//  [X] Platform: Multi-viewport support (multiple windows). Enable with 'io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable'.
 
 // You can copy and use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
 // If you are new to Dear ImGui, read documentation from the docs/ folder + read the top of imgui.cpp.

docs/BACKENDS.md

@@ -56,7 +56,7 @@ List of Platforms Backends:
     imgui_impl_osx.mm         ; macOS native API (not as feature complete as glfw/sdl backends)
     imgui_impl_sdl.cpp        ; SDL2 (Windows, macOS, Linux, iOS, Android) https://www.libsdl.org
     imgui_impl_win32.cpp      ; Win32 native API (Windows)
-    imgui_impl_glut.cpp       ; GLUT/FreeGLUT (this is prehistoric software and absolutely not recommended today!)
+    imgui_impl_glut.cpp       ; GLUT/FreeGLUT (absolutely not recommended in 2020!)
 
 List of Renderer Backends:
 

docs/CHANGELOG.txt

@@ -32,16 +32,83 @@ HOW TO UPDATE?
 
 
 -----------------------------------------------------------------------
- VERSION 1.80 (Released 2021-01-21)
+ DOCKING+MULTI-VIEWPORT BRANCH (In Progress)
+-----------------------------------------------------------------------
+
+DOCKING FEATURES
+
+- Added Docking system: [BETA] (#2109, #351)
+  - Added ImGuiConfigFlags_DockingEnable flag to enable Docking.
+    Set with `io.ConfigFlags |= ImGuiConfigFlags_DockingEnable;`.
+  - Added DockSpace(), DockSpaceOverViewport() API.
+  - Added ImGuiDockNodeFlags flags for DockSpace().
+  - Added SetNextWindowDockID(), SetNextWindowClass() API.
+  - Added GetWindowDockID(), IsWindowDocked() API.
+  - Added ImGuiWindowFlags_NoDocking window flag to disable the possibility for a window to be docked.
+    Popup, Menu and Child windows always have the ImGuiWindowFlags_NoDocking flag set.
+  - Added ImGuiWindowClass to specify advanced docking/viewport related flags via SetNextWindowClass().
+  - Added io.ConfigDockingNoSplit option.
+  - Added io.ConfigDockingWithShift option.
+  - Added io.ConfigDockingAlwaysTabBar option.
+  - Added io.ConfigDockingTransparentPayload option.
+  - Style: Added ImGuiCol_DockingPreview, ImGuiCol_DockingEmptyBg colors.
+  - Demo: Added "DockSpace" example app showcasing use of explicit dockspace nodes.
+
+MULTI-VIEWPORT FEATURES (was previously 'viewport' branch, merged into 'docking')
+
+Breaking Changes:
+
+- IMPORTANT: When multi-viewports are enabled (with io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable),
+  all coordinates/positions will be in your natural OS coordinates space. It means that:
+   - Reference to hard-coded positions such as in SetNextWindowPos(ImVec2(0,0)) are _probably_ not what you want anymore.
+     Use GetMainViewport()->Pos to offset hard-coded positions, e.g. SetNextWindowPos(GetMainViewport()->Pos).
+   - Likewise io.MousePos and GetMousePos() will use OS coordinates.
+     If you query mouse positions to interact with non-imgui coordinates you will need to offset them.
+     e.g. subtract GetWindowViewport()->Pos.
+- Render function: the ImDrawData structure now contains 'DisplayPos' and 'DisplaySize' fields.
+  To support multi-viewport, you need to use those values when creating your orthographic projection matrix.
+  Use 'draw_data->DisplaySize' instead of 'io.DisplaySize', and 'draw_data->DisplayPos' instead of (0,0) as the upper-left point.
+  You need to subtract 'draw_data->DisplayPos' from your scissor rectangles to convert them from global coordinates to frame-buffer coordinates.
+- IO: Moved IME support functions from io.ImeSetInputScreenPosFn, io.ImeWindowHandle to the PlatformIO api.
+- IO: Removed io.DisplayVisibleMin, io.DisplayVisibleMax settings (they were marked obsoleted, used to clip within the (0,0)..(DisplaySize) range).
+
+Other changes:
+(FIXME: This need a fuller explanation!)
+
+- Added ImGuiPlatformIO structure and GetPlatformIO().
+  Similarly to ImGuiIO and GetIO(), this structure is the main point of communication for backends supporting multi-viewports.
+- Added ImGuiPlatformMonitor to feed OS monitor information in the ImGuiPlatformIO::Monitors.
+- Added GetMainViewport().
+- Added GetWindowViewport(), SetNextWindowViewport().
+- Added GetWindowDpiScale().
+- Added GetOverlayDrawList(ImGuiViewport* viewport).
+  The no-parameter version of GetOverlayDrawList() return the overlay for the current window's viewport.
+- Added UpdatePlatformWindows(), RenderPlatformWindows(), DestroyPlatformWindows() for usage for application core.
+- Added FindViewportByID(), FindViewportByPlatformHandle() for usage by backends.
+- Added ImGuiConfigFlags_ViewportsEnable configuration flag and other viewport options.
+- Added io.ConfigViewportsNoAutoMerge, io.ConfigViewportsNoTaskBarIcon, io.ConfigViewportsNoDecoration, io.ConfigViewportsNoDefaultParent options.
+- Added ImGuiBackendFlags_PlatformHasViewports, ImGuiBackendFlags_RendererHasViewports, ImGuiBackendFlags_HasMouseHoveredViewport backend flags.
+- Added io.MainViewport, io.Viewports, io.MouseHoveredViewport (MouseHoveredViewport is optional _even_ for multi-viewport support).
+- Added ImGuiViewport structure, ImGuiViewportFlags flags.
+- Added ImGuiWindowClass and SetNextWindowClass() for passing viewport related hints to the OS/platform back-end.
+- Examples: Renderer: OpenGL2, OpenGL3, DirectX11, DirectX12, Vulkan: Added support for multi-viewports.
+- Examples: Platforms: Win32, GLFW, SDL2: Added support for multi-viewports.
+  Note that Linux/Mac still have inconsistent support for multi-viewports. If you want to help see https://github.com/ocornut/imgui/issues/2117.
+- Examples: Win32: Added DPI-related helpers to access DPI features without requiring the latest Windows SDK at compile time,
+  and without requiring Windows 10 at runtime.
+- Examples: Vulkan: Added various optional helpers in imgui_impl_vulkan.h (they are used for multi-viewport support)
+  to make the examples main.cpp easier to read.
+
+
+-----------------------------------------------------------------------
+ VERSION 1.80 (In Progress)
 -----------------------------------------------------------------------
 
 Breaking Changes:
 
-- Added imgui_tables.cpp file! Manually constructed project files will need the new file added! (#3740)
+- Added imgui_tables.cpp file! Manually constructed project files will need the new file added!
 - Backends: moved all backends files (imgui_impl_XXXX.cpp, imgui_impl_XXXX.h) from examples/ to backends/. (#3513)
-- Renamed ImDrawList::AddBezierCurve() to ImDrawList::AddBezierCubic(). Kept inline redirection function (will obsolete).
-- Renamed ImDrawList::PathBezierCurveTo() to ImDrawList::PathBezierCubicCurveTo(). Kept inline redirection function (will obsolete).
-- Removed redirecting functions/enums names that were marked obsolete in 1.60 (April 2018):
+- Removed redirecting functions/enums names that were marked obsolete in 1.60 (April 2017):
   - io.RenderDrawListsFn pointer                -> use ImGui::GetDrawData() value and call the render function of your backend
   - ImGui::IsAnyWindowFocused()                 -> use ImGui::IsWindowFocused(ImGuiFocusedFlags_AnyWindow)
   - ImGui::IsAnyWindowHovered()                 -> use ImGui::IsWindowHovered(ImGuiHoveredFlags_AnyWindow)
@@ -50,64 +117,45 @@ Breaking Changes:
 - Removed redirecting functions/enums names that were marked obsolete in 1.61 (May 2018):
   - InputFloat (... int decimal_precision ...)  -> use InputFloat (... const char* format ...) with format = "%.Xf" where X was value for decimal_precision.
   - same for InputFloat2()/InputFloat3()/InputFloat4() variants taking a `int decimal_precision` parameter.
-- Removed redirecting functions/enums names that were marked obsolete in 1.63 (August 2018):
-  - ImGui::IsItemDeactivatedAfterChange()       -> use ImGui::IsItemDeactivatedAfterEdit().
-  - ImGuiCol_ModalWindowDarkening               -> use ImGuiCol_ModalWindowDimBg
-  - ImGuiInputTextCallback                      -> use ImGuiTextEditCallback
-  - ImGuiInputTextCallbackData                  -> use ImGuiTextEditCallbackData
 - If you were still using the old names, while you are cleaning up, considering enabling
   IMGUI_DISABLE_OBSOLETE_FUNCTIONS in imconfig.h even temporarily to have a pass at finding
   and removing up old API calls, if any remaining.
-- Internals: Columns: renamed undocumented/internals ImGuiColumnsFlags_* to ImGuiOldColumnFlags_* to reduce 
-  confusion with Tables API. Keep redirection enums (will obsolete). (#125, #513, #913, #1204, #1444, #2142, #2707)
-- Renamed io.ConfigWindowsMemoryCompactTimer to io.ConfigMemoryCompactTimer as the feature now applies
+- Columns: renamed undocumented/internals ImGuiColumnsFlags_* to ImGuiOldColumnFlags_* in prevision of
+  incoming Tables API. Keep redirection enums (will obsolete). (#125, #513, #913, #1204, #1444, #2142, #2707)
+- Renamed io.ConfigWindowsMemoryCompactTimer to io.ConfigMemoryCompactTimer as the feature will apply
   to other data structures. (#2636)
 
 Other Changes:
 
-- Tables: added new Tables Beta API as a replacement for old Columns. (#3740, #2957, #125)
-  Check out 'Demo->Tables' for many demos.
-  Read API comments in imgui.h for details. Read extra commentary in imgui_tables.cpp.
-  - Added 16 functions: 
-     - BeginTable(), EndTable()
-     - TableNextRow(), TableNextColumn(), TableSetColumnIndex()
-     - TableSetupColumn(), TableSetupScrollFreeze()
-     - TableHeadersRow(), TableHeader()
-     - TableGetRowIndex(), TableGetColumnCount(), TableGetColumnIndex(), TableGetColumnName(), TableGetColumnFlags()
-     - TableGetSortSpecs(), TableSetBgColor()
-  - Added 3 flags sets: 
-    - ImGuiTableFlags (29 flags for: features, decorations, sizing policies, padding, clipping, scrolling, sorting etc.)
-    - ImGuiTableColumnFlags (24 flags for: width policies, default settings, sorting options, indentation options etc.)
-    - ImGuiTableRowFlags (1 flag for: header row)
-  - Added 2 structures: ImGuiTableSortSpecs, ImGuiTableColumnSortSpecs
-  - Added 2 enums: ImGuiSortDirection, ImGuiTableBgTarget
-  - Added 1 style variable: ImGuiStyleVar_CellPadding
-  - Added 5 style colors: ImGuiCol_TableHeaderBg, ImGuiCol_TableBorderStrong, ImGuiCol_TableBorderLight, ImGuiCol_TableRowBg, ImGuiCol_TableRowBgAlt.
+- Tables: added new Tables Beta API as a replacement for old Columns. (#2957, #125)
+  Check out 'Demo->Tables' for many demos + API comments in imgui.h for details.
+  - Added 16 functions: BeginTable(), EndTable(), 
+                        TableNextRow(), TableNextColumn(), TableSetColumnIndex(), TableGetColumnIndex(), TableGetRowIndex(), 
+                        TableSetupColumn(), TableSetupScrollFreeze(),
+                        TableHeadersRow(), TableHeader(), TableSetBgColor(), TableGetSortSpecs(),
+                        TableGetColumnCount(), TableGetColumnName(), TableGetColumnFlags().
+  - Added 2 structures: ImGuiTableSortSpecs, ImGuiTableColumnSortSpecs.
+  - Added 2 enums:      ImGuiSortDirection, ImGuiTableBgTarget.
+  - Added 3 flags sets: ImGuiTableFlags (27 flags), ImGuiTableColumnFlags (24 flags), ImGuiTableRowFlags (1 flags).
+  - Added 5 colors:     ImGuiCol_TableHeaderBg, ImGuiCol_TableBorderStrong, ImGuiCol_TableBorderLight, ImGuiCol_TableRowBg, ImGuiCol_TableRowBgAlt.
+  - Added 1 style var:  ImGuiStyleVar_CellPadding.
 - Tab Bar: Made it possible to append to an existing tab bar by calling BeginTabBar()/EndTabBar() again.
 - Tab Bar: Fixed using more than 128 tabs in a tab bar (scrolling policy recommended).
 - Tab Bar: Do not display a tooltip if the name already fits over a given tab. (#3521)
 - Tab Bar: Fixed minor/unlikely bug skipping over a button when scrolling left with arrows.
-- Tab Bar: Requested ideal content size (for auto-fit) doesn't affect horizontal scrolling. (#3414)
 - Drag and Drop: Fix losing drop source ActiveID (and often source tooltip) when opening a TreeNode()
   or CollapsingHeader() while dragging. (#1738)
-- Drag and Drop: Fix drag and drop to tie same-size drop targets by chosen the later one. Fixes dragging
+- Drag and Drop: Fix drag and drop to tie same-size drop targets by choosen the later one. Fixes dragging
   into a full-window-sized dockspace inside a zero-padded window. (#3519, #2717) [@Black-Cat]
-- Checkbox: Added CheckboxFlags() helper with int* type (internals have a template version, not exposed).
-- Clipper: Fixed incorrect end-list positioning when using ImGuiListClipper with 1 item (bug in 1.79). (#3663) [@nyorain]
+- Checkbox: Added CheckboxFlags() helper with int* type.
 - InputText: Fixed updating cursor/selection position when a callback altered the buffer in a way
   where the byte count is unchanged but the decoded character count changes. (#3587) [@gqw]
-- InputText: Fixed switching from single to multi-line while preserving same ID.
-- Combo: Fixed using IsItemEdited() after Combo() not matching the return value from Combo(). (#2034)
-- DragFloat, DragInt: very slightly increased mouse drag threshold + expressing it as a factor of default value.
-- DragFloat, DragInt: added experimental io.ConfigDragClickToInputText feature to enable turning DragXXX widgets
-  into text input with a simple mouse click-release (without moving). (#3737)
+- InputText: Fixed swiching from single to multi-line while preserving same ID.
 - Nav: Fixed IsItemFocused() from returning false when Nav highlight is hidden because mouse has moved.
   It's essentially been always the case but it doesn't make much sense. Instead we will aim at exposing
   feedback and control of keyboard/gamepad navigation highlight and mouse hover disable flag. (#787, #2048)
 - Metrics: Fixed mishandling of ImDrawCmd::VtxOffset in wireframe mesh renderer.
 - Metrics: Rebranded as "Dear ImGui Metrics/Debugger" to clarify its purpose.
-- ImDrawList: Added ImDrawList::AddQuadBezierCurve(), ImDrawList::PathQuadBezierCurveTo() quadratic bezier
-  helpers. (#3127, #3664, #3665) [@aiekick]
 - Fonts: Updated GetGlyphRangesJapanese() to include a larger 2999 ideograms selection of Joyo/Jinmeiyo
   kanjis, from the previous 1946 ideograms selection. This will consume a some more memory but be generally
   much more fitting for Japanese display, until we switch to a more dynamic atlas. (#3627) [@vaiorabbit]
@@ -122,37 +170,25 @@ Other Changes:
 - Misc: Made EndFrame() assertion for key modifiers being unchanged during the frame (added in 1.76) more
   lenient, allowing full mid-frame releases. This is to accommodate the use of mid-frame modal native
   windows calls, which leads backends such as GLFW to send key clearing events on focus loss. (#3575)
-- Style: Changed default style.WindowRounding value to 0.0f (matches default for multi-viewports).
-- Style: Reduced the size of the resizing grip, made alpha less prominent.
-- Style: Classic: Increase the default alpha value of WindowBg to be closer to other styles.
 - Demo: Clarify usage of right-aligned items in Demo>Layout>Widgets Width.
 - Backends: OpenGL3: Use glGetString(GL_VERSION) query instead of glGetIntegerv(GL_MAJOR_VERSION, ...)
   when the later returns zero (e.g. Desktop GL 2.x). (#3530) [@xndcn]
-- Backends: OpenGL2: Backup and restore GL_SHADE_MODEL and disable GL_NORMAL_ARRAY state to increase 
-  compatibility with legacy code. (#3671)
 - Backends: OpenGL3: Backup and restore GL_PRIMITIVE_RESTART state. (#3544) [@Xipiryon]
-- Backends: OpenGL2, OpenGL3: Backup and restore GL_STENCIL_TEST enable state. (#3668)
-- Backends: Vulkan: Added support for specifying which sub-pass to reference during VkPipeline creation. (@3579) [@bdero]
-- Backends: DX12: Improve Windows 7 compatibility (for D3D12On7) by loading d3d12.dll dynamically. (#3696) [@Mattiwatti]
+- Backends: Vulkan: Added support for specifying which subpass to reference during VkPipeline creation. (@3579) [@bdero]
 - Backends: Win32: Fix setting of io.DisplaySize to invalid/uninitialized data after hwnd has been closed.
 - Backends: OSX: Fix keypad-enter key not working on MacOS. (#3554) [@rokups, @lfnoise]
 - Examples: Apple+Metal: Consolidated/simplified to get closer to other examples. (#3543) [@warrenm]
 - Examples: Apple+Metal: Forward events down so OS key combination like Cmd+Q can work. (#3554) [@rokups]
 - Examples: Emscripten: Renamed example_emscripten/ to example_emscripten_opengl3/. (#3632)
-- Examples: Emscripten: Added 'make serve' helper to spawn a web-server on localhost. (#3705) [@Horki]
-- Examples: DirectX12: Move ImGui::Render() call above the first barrier to clarify its lack of effect on the graphics pipe.
 - CI: Fix testing for Windows DLL builds. (#3603, #3601) [@iboB]
-- Docs: Improved the wiki and added a https://github.com/ocornut/imgui/wiki/Useful-Widgets page. [@Xipiryon]
-- Docs: Split examples/README.txt into docs/BACKENDS.md and docs/EXAMPLES.md, and improved them.
-- Docs: Consistently renamed all occurrences of "binding" and "back-end" to "backend" in comments and docs.
+- Docs: Split examples/README.txt into docs/BACKENDS.md and docs/EXAMPLES.md improved them.
+- Docs: Consistently renamed all occurences of "binding" and "back-end" to "backend" in comments and docs.
 
 
 -----------------------------------------------------------------------
  VERSION 1.79 (Released 2020-10-08)
 -----------------------------------------------------------------------
 
-Decorated log: https://github.com/ocornut/imgui/releases/tag/v1.79
-
 Breaking Changes:
 
 - Fonts: Removed ImFont::DisplayOffset in favor of ImFontConfig::GlyphOffset. DisplayOffset was applied
@@ -245,8 +281,6 @@ Other Changes:
  VERSION 1.78 (Released 2020-08-18)
 -----------------------------------------------------------------------
 
-Decorated log: https://github.com/ocornut/imgui/releases/tag/v1.78
-
 Breaking Changes:
 
 - Obsoleted use of the trailing 'float power=1.0f' parameter for those functions: [@Shironekoben, @ocornut]
@@ -1184,6 +1218,7 @@ Breaking Changes:
 - Renamed ImFontAtlas::GlyphRangesBuilder to ImFontGlyphRangesBuilder. Kept redirection typedef (will obsolete).
 
 Other Changes:
+
 - Added BETA api for Tab Bar/Tabs widgets: (#261, #351)
   - Added BeginTabBar(), EndTabBar(), BeginTabItem(), EndTabItem(), SetTabItemClosed() API.
   - Added ImGuiTabBarFlags flags for BeginTabBar().

docs/EXAMPLES.md

@@ -198,9 +198,9 @@ This is quite long and tedious, because: DirectX12.
 
 **Building**
 
-Unfortunately nowadays it is still tedious to create and maintain portable build files using external
+Unfortunately in 2020 it is still tedious to create and maintain portable build files using external
 libraries (the kind we're using here to create a window and render 3D triangles) without relying on
-third party software and build systems. For most examples here we choose to provide:
+third party software. For most examples here we choose to provide:
  - Makefiles for Linux/OSX
  - Batch files for Visual Studio 2008+
  - A .sln project file for Visual Studio 2012+

docs/FAQ.md

@@ -23,7 +23,7 @@ or view this file with any Markdown viewer.
 | [I integrated Dear ImGui in my engine and some elements are clipping or disappearing when I move windows around..](#q-i-integrated-dear-imgui-in-my-engine-and-some-elements-are-clipping-or-disappearing-when-i-move-windows-around) |
 | [I integrated Dear ImGui in my engine and some elements are displaying outside their expected windows boundaries..](#q-i-integrated-dear-imgui-in-my-engine-and-some-elements-are-displaying-outside-their-expected-windows-boundaries) |
 | **Q&A: Usage** |
-| **[Why is my widget not reacting when I click on it?<br>How can I have widgets with an empty label?<br>How can I have multiple widgets with the same label?](#q-why-is-my-widget-not-reacting-when-i-click-on-it)** |
+| **[Why is my widget not reacting when I click on it?<br>How can I have multiple widgets with the same label?<br>Why are multiple widgets reacting when I interact with one?](#q-why-is-my-widget-not-reacting-when-i-click-on-it)** |
 | [How can I display an image? What is ImTextureID, how does it work?](#q-how-can-i-display-an-image-what-is-imtextureid-how-does-it-work)|
 | [How can I use my own math types instead of ImVec2/ImVec4?](#q-how-can-i-use-my-own-math-types-instead-of-imvec2imvec4) |
 | [How can I interact with standard C++ types (such as std::string and std::vector)?](#q-how-can-i-interact-with-standard-c-types-such-as-stdstring-and-stdvector) |
@@ -214,6 +214,8 @@ Button("OK");          // Label = "OK",     ID = hash of ("MyOtherWindow", "OK")
 End();
 ```
 
+We used "..." above to signify whatever was already pushed to the ID stack previously:
+
 - If you have a same ID twice in the same location, you'll have a conflict:
 ```cpp
 Button("OK");
@@ -427,8 +429,10 @@ provide similar or better string helpers.
 ### Q: How can I display custom shapes? (using low-level ImDrawList API)
 
 - You can use the low-level `ImDrawList` api to render shapes within a window.
+
 ```cpp
-ImGui::Begin("My shapes");
+if (!ImGui::Begin("My shapes"))
+    return;
 
 ImDrawList* draw_list = ImGui::GetWindowDrawList();
 

docs/README.md

@@ -52,7 +52,8 @@ Result:
 Code:
 ```cpp
 // Create a window called "My First Tool", with a menu bar.
-ImGui::Begin("My First Tool", &my_tool_active, ImGuiWindowFlags_MenuBar);
+if (!ImGui::Begin("My First Tool", &my_tool_active, ImGuiWindowFlags_MenuBar))
+    return;
 if (ImGui::BeginMenuBar())
 {
     if (ImGui::BeginMenu("File"))
@@ -120,7 +121,7 @@ Officially maintained backends/bindings (in repository):
 - Frameworks: Emscripten, Allegro5, Marmalade.
 
 [Third-party backends/bindings](https://github.com/ocornut/imgui/wiki/Bindings) wiki page:
-- Languages: C, C# and: Beef, ChaiScript, Crystal, D, Go, Haskell, Haxe/hxcpp, Java, JavaScript, Julia, Kotlin, Lobster, Lua, Odin, Pascal, PureBasic, Python, Ruby, Rust, Swift...
+- Languages: C, C# and: Beef, ChaiScript, Crystal, D, Go, Haskell, Haxe/hxcpp, Java, JavaScript, Julia, Kotlin, Lua, Odin, Pascal, PureBasic, Python, Ruby, Rust, Swift...
 - Frameworks: AGS/Adventure Game Studio, Amethyst, bsf, Cinder, Cocos2d-x, Diligent Engine, Flexium, GML/Game Maker Studio2, Godot, GTK3+OpenGL3, Irrlicht Engine, LÖVE+LUA, Magnum, NanoRT, nCine, Nim Game Lib, Ogre, openFrameworks, OSG/OpenSceneGraph, Orx, Photoshop, px_render, Qt/QtDirect3D, SFML, Sokol, Unity, Unreal Engine 4, vtk, Win32 GDI, WxWidgets.
 - Note that C bindings ([cimgui](https://github.com/cimgui/cimgui)) are auto-generated, you can use its json/lua output to generate bindings for other languages.
 
@@ -131,7 +132,8 @@ Also see [Wiki](https://github.com/ocornut/imgui/wiki) for more links and ideas.
 
 ### Upcoming Changes
 
-Some of the goals for 2021 are:
+Some of the goals for 2020 are:
+- Work on new Tables API (to replace Columns). (see [#2957](https://github.com/ocornut/imgui/issues/2957), in public [tables](https://github.com/ocornut/imgui/tree/tables) branch looking for feedback)
 - Work on Docking (see [#2109](https://github.com/ocornut/imgui/issues/2109), in public [docking](https://github.com/ocornut/imgui/tree/docking) branch)
 - Work on Multi-Viewport / Multiple OS windows. (see [#1542](https://github.com/ocornut/imgui/issues/1542), in public [docking](https://github.com/ocornut/imgui/tree/docking) branch looking for feedback)
 - Work on gamepad/keyboard controls. (see [#787](https://github.com/ocornut/imgui/issues/787))
@@ -150,7 +152,7 @@ Custom engine
 Custom engine
 [![screenshot tool](https://raw.githubusercontent.com/wiki/ocornut/imgui/web/v160/editor_white_preview.jpg)](https://raw.githubusercontent.com/wiki/ocornut/imgui/web/v160/editor_white.png)
 
-[Tracy Profiler](https://github.com/wolfpld/tracy)
+[Tracy Profiler](https://bitbucket.org/wolfpld/tracy)
 ![tracy profiler](https://raw.githubusercontent.com/wiki/ocornut/imgui/web/v176/tracy_profiler.png)
 
 ### Support, Frequently Asked Questions (FAQ)

docs/TODO.txt

@@ -129,6 +129,18 @@ It's mostly a bunch of personal notes, probably incomplete. Feel free to query i
  - group: IsHovered() after EndGroup() covers whole aabb rather than the intersection of individual items. Is that desirable?
  - group: merge deactivation/activation within same group (fwd WasEdited flag). (#2550)
 
+ - columns: sizing policy (e.g. for each column: fixed size, %, fill, distribute default size among fills) (#513, #125)
+ - columns: add a conditional parameter to SetColumnOffset() (#513, #125)
+ - columns: headers. re-orderable. (#513, #125)
+ - columns: optional sorting modifiers (up/down), sort list so sorting can be done multi-criteria. notify user when sort order changed.
+ - columns: option to alternate background colors on odd/even scanlines.
+ - columns: allow columns to recurse.
+ - columns: allow a same columns set to be interrupted by e.g. CollapsingHeader and resume with columns in sync when moving them.
+ - columns: sizing is lossy when columns width is very small (default width may turn negative etc.)
+ - columns: separator function or parameter that works within the column (currently Separator() bypass all columns) (#125)
+ - columns: flag to add horizontal separator above/below)
+ - columns/layout: setup minimum line height (equivalent of automatically calling AlignFirstTextHeightToWidgets)
+
 !- color: the color conversion helpers/types are a mess and needs sorting out.
  - color: (api breaking) ImGui::ColorConvertXXX functions should be loose ImColorConvertXX to match imgui_internals.h
 
@@ -151,8 +163,36 @@ It's mostly a bunch of personal notes, probably incomplete. Feel free to query i
  - separator: width, thickness, centering (#1643)
  - splitter: formalize the splitter idiom into an official api (we want to handle n-way split) (#319)
 
- - dock: merge docking branch (#2109)
- - dock: dock out from a collapsing header? would work nicely but need emitting window to keep submitting the code.
+ - docking: merge docking branch (#2109)
+ - docking: B: ordering currently held in tab bar should be implicitly held by windows themselves (also see #2304)
+ - docking: B- tab bar: the order/focus restoring code could be part of TabBar and not DockNode? (#8)
+ - docking: B~ rework code to be able to lazily create tab bar instance in a single place. The _Unsorted tab flag could be replacing a trailing-counter in DockNode?
+ - docking: B~ fully track windows/settings reference in dock nodes. perhaps find a representation that allows facilitate use of dock builder functions.
+ - docking: B~ Unreal style document system (requires low-level controls of dockspace serialization fork/copy/delete). this is mostly working but the DockBuilderXXX api are not exposed/finished.
+ - docking: B: when docking outer, perform size locking on neighbors nodes the same way we do it with splitters, so other nodes are not resized.
+ - docking: B~ central node resizing behavior incorrect.
+ - docking: B: changing title font/style per-window is not supported as dock nodes are created in NewFrame.
+ - docking: B- dock node inside its own viewports creates 1 temporary viewport per window on startup before ditching them (doesn't affect the user nor request platform windows to be created, but unnecessary)
+ - docking: B- resize sibling locking behavior may be less desirable if we merged same-axis sibling in a same node level?
+ - docking: B- single visible node part of a hidden split hierarchy (OnlyNodeWithWindows != NULL) should show a normal title bar (not a tab bar)
+ - docking: B~ SetNextWindowDock() calls (with conditional) -> defer everything to DockContextUpdate (repro: Documents->[X]Windows->Dock 1 elsewhere->Click Redock All
+ - docking: B~ tidy up tab list popup buttons features (available with manual tab-bar, see ImGuiTabBarFlags_NoTabListPopupButton code, not used by docking nodes)
+ - docking: B- SetNextWindowDockId(0) with a second Begin() in the frame will asserts
+ - docking: B: resize grip drawn in host window typically appears under scrollbar.
+ - docking: B: resize grip auto-resize on multiple node hierarchy doesn't make much sense or should be improved?
+ - docking: B- SetNextWindowFocus() doesn't seem to apply if the window is hidden this frame, need repro (#4)
+ - docking: B- resizing a dock tree small currently has glitches (overlapping collapse and close button, etc.)
+ - docking: B- dpi: look at interaction with the hi-dpi and multi-dpi stuff.
+ - docking: B- tab bar: appearing on first frame with a dumb layout would do less harm that not appearing? (when behind dynamic branch) or store titles + render in EndTabBar()
+ - docking: B- tab bar: make selected tab always shows its full title?
+ - docking: B- hide close button on single tab bar?
+ - docking: B- nav: design interactions so nav controls can dock/undock
+ - docking: B- dockspace: flag to lock the dock tree and/or sizes (ImGuiDockNodeFlags_Locked?)
+ - docking: B- reintroduce collapsing a floating dock node. also collapsing a docked dock node!
+ - docking: B- allow dragging a non-floating dock node by clicking on the title-bar-looking section (not just the collapse/menu button)
+ - docking: B- option to remember undocked window size? (instead of keeping their docked size) (relate to #2104)
+ - docking: C- nav: CTRL+TAB highlighting tabs shows the mismatch between focus-stack and tab-order (not visible in VS because it doesn't highlight the tabs)
+ - docking: C- after a dock/undock, the Scrollbar Status update in Begin() should use an updated e.g. size_y_for_scrollbars to avoid a 1 frame scrollbar flicker.
 
  - tabs: "there is currently a problem because TabItem() will try to submit their own tooltip after 0.50 second, and this will have the effect of making your tooltip flicker once." -> tooltip priority work
  - tabs: close button tends to overlap unsaved-document star
@@ -352,6 +392,20 @@ It's mostly a bunch of personal notes, probably incomplete. Feel free to query i
  - focus: SetKeyboardFocusHere() on with >= 0 offset could be done on same frame (else latch and modulate on beginning of next frame)
  - focus: unable to use SetKeyboardFocusHere() on clipped widgets. (#787)
 
+ - viewport: make it possible to have no main/hosting viewport
+ - viewport: We set ImGuiViewportFlags_NoFocusOnAppearing in a way that is required for GLFW/SDL binding, but could be handled better without
+   on a custom e.g. Win32 bindings. It prevents newly dragged-out viewports from taking the focus, which makes ALT+F4 more ambiguous.
+ - viewport: not focusing newly undocked viewport means clicking back on previous one doesn't bring OS window to front.
+ - viewport: with platform decoration enabled, platform may force constraint (e.g. minimum size)
+ - viewport: use getfocus/setfocus api to synchronize imgui<>platform focus better (e.g imgui-side ctrl-tab can focus os window, OS initial setup and alt-tab can focus imgui window etc.)
+ - viewport: store per-viewport/monitor DPI in .ini file so an application reload or main window changing DPI on reload can be properly patched for.
+ - viewport: implicit/fallback Debug window can hog a zombie viewport (harmless, noisy?) > could at least clear out the reference on a per session basis?
+ - viewport: need to clarify how to use GetMousePos() from a user point of view.
+ - platform: glfw: no support for ImGuiBackendFlags_HasMouseHoveredViewport.
+ - platform: sdl: no support for ImGuiBackendFlags_HasMouseHoveredViewport. maybe we could use SDL_GetMouseFocus() / SDL_WINDOW_MOUSE_FOCUS if imgui could fallback on its heuristic when NoInputs is set
+ - platform: sdl: no refresh of monitor/display (SDL doesn't seem to have an event for it).
+ - platform: sdl: multi-viewport + minimized window seems to break mouse wheel events (at least under Win32).
+
  - inputs: we need an explicit flag about whether the imgui window is focused, to be able to distinguish focused key releases vs alt-tabbing all release behaviors.
  - inputs: rework IO system to be able to pass actual ordered/timestamped events. use an event queue? (~#335, #71)
  - inputs: support track pad style scrolling & slider edit.

examples/example_allegro5/main.cpp

@@ -28,6 +28,7 @@ int main(int, char**)
     ImGui::CreateContext();
     ImGuiIO& io = ImGui::GetIO(); (void)io;
     //io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;  // Enable Keyboard Controls
+    io.ConfigFlags |= ImGuiConfigFlags_DockingEnable;        // Enable Docking
 
     // Setup Dear ImGui style
     ImGui::StyleColorsDark();

examples/example_apple_opengl2/main.mm

@@ -250,6 +250,7 @@
     ImGuiIO& io = ImGui::GetIO(); (void)io;
     //io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;     // Enable Keyboard Controls
     //io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad;      // Enable Gamepad Controls
+    io.ConfigFlags |= ImGuiConfigFlags_DockingEnable;           // Enable Docking
 
     // Setup Dear ImGui style
     ImGui::StyleColorsDark();

examples/example_emscripten_opengl3/Makefile

@@ -7,16 +7,15 @@
 # (On Windows, you may need to execute emsdk_env.bat or encmdprompt.bat ahead)
 #
 # Running `make` will produce three files:
-#  - web/index.html
-#  - web/index.js
-#  - web/index.wasm
+#  - example_emscripten_opengl3.html
+#  - example_emscripten_opengl3.js
+#  - example_emscripten_opengl3.wasm
 #
 # All three are needed to run the demo.
 
 CC = emcc
 CXX = em++
-WEB_DIR = web
-EXE = $(WEB_DIR)/index.html
+EXE = example_emscripten_opengl3.html
 IMGUI_DIR = ../..
 SOURCES = main.cpp
 SOURCES += $(IMGUI_DIR)/imgui.cpp $(IMGUI_DIR)/imgui_demo.cpp $(IMGUI_DIR)/imgui_draw.cpp $(IMGUI_DIR)/imgui_tables.cpp $(IMGUI_DIR)/imgui_widgets.cpp
@@ -79,14 +78,8 @@ LDFLAGS += --shell-file shell_minimal.html
 all: $(EXE)
 	@echo Build complete for $(EXE)
 
-$(WEB_DIR):
-	mkdir $@
-
-serve: all
-	python3 -m http.server -d $(WEB_DIR)
-
-$(EXE): $(OBJS) $(WEB_DIR)
-	$(CXX) -o $@ $(OBJS) $(LIBS) $(LDFLAGS)
+$(EXE): $(OBJS)
+	$(CXX) -o $@ $^ $(LIBS) $(LDFLAGS)
 
 clean:
-	rm -rf $(OBJS) $(WEB_DIR)
+	rm -f $(EXE) $(OBJS) *.js *.wasm *.wasm.pre

examples/example_emscripten_opengl3/README.md

@@ -1,3 +1,4 @@
+
 ## How to Build
 
 - You need to install Emscripten from https://emscripten.org/docs/getting_started/downloads.html, and have the environment variables set, as described in https://emscripten.org/docs/getting_started/downloads.html#installation-instructions
@@ -8,13 +9,10 @@
 ## How to Run
 
 To run on a local machine:
-- `make serve` will use Python3 to spawn a local webserver, you can then browse http://localhost:8000 to access your build.
-- Otherwise, generally you will need a local webserver:
-  - Quoting [https://emscripten.org/docs/getting_started](https://emscripten.org/docs/getting_started/Tutorial.html#generating-html):<br>
+- Generally you may need a local webserver. Quoting [https://emscripten.org/docs/getting_started](https://emscripten.org/docs/getting_started/Tutorial.html#generating-html):<br>
 _"Unfortunately several browsers (including Chrome, Safari, and Internet Explorer) do not support file:// [XHR](https://emscripten.org/docs/site/glossary.html#term-xhr) requests, and can’t load extra files needed by the HTML (like a .wasm file, or packaged file data as mentioned lower down). For these browsers you’ll need to serve the files using a [local webserver](https://emscripten.org/docs/getting_started/FAQ.html#faq-local-webserver) and then open http://localhost:8000/hello.html."_
-  - Emscripten SDK has a handy `emrun` command: `emrun web/example_emscripten_opengl3.html --browser firefox` which will spawn a temporary local webserver (in Firefox). See https://emscripten.org/docs/compiling/Running-html-files-with-emrun.html for details.
-  - You may use Python 3 builtin webserver: `python -m http.server -d web` (this is what `make serve` uses).
-  - You may use Python 2 builtin webserver: `cd web && python -m SimpleHTTPServer`.
+- Emscripten SDK has a handy `emrun` command: `emrun example_emscripten_opengl3.html` which will spawn a temporary local webserver. See https://emscripten.org/docs/compiling/Running-html-files-with-emrun.html for details.
+- Otherwise you may use Python builtin webserver: `python -m http.server` in Python 3 or `python -m SimpleHTTPServer` in Python 2. After doing that, you can visit http://localhost:8000/.
 
 ## Obsolete features:
 

examples/example_emscripten_opengl3/main.cpp

@@ -62,8 +62,9 @@ int main(int, char**)
     IMGUI_CHECKVERSION();
     ImGui::CreateContext();
     ImGuiIO& io = ImGui::GetIO(); (void)io;
-    //io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;     // Enable Keyboard Controls
+    io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;       // Enable Keyboard Controls
     //io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad;      // Enable Gamepad Controls
+    io.ConfigFlags |= ImGuiConfigFlags_DockingEnable;           // Enable Docking
 
     // For an Emscripten build we are disabling file-system access, so let's not attempt to do a fopen() of the imgui.ini file.
     // You may manually call LoadIniSettingsFromMemory() to load settings from your own storage.

examples/example_glfw_opengl2/build_win32.bat

@@ -1,8 +1,3 @@
 @REM Build for Visual Studio compiler. Run your copy of vcvars32.bat or vcvarsall.bat to setup command-line compiler.
-@set OUT_DIR=Debug
-@set OUT_EXE=example_glfw_opengl2
-@set INCLUDES=/I..\.. /I..\..\backends /I..\libs\glfw\include
-@set SOURCES=main.cpp ..\..\backends\imgui_impl_opengl2.cpp ..\..\backends\imgui_impl_glfw.cpp ..\..\imgui*.cpp
-@set LIBS=/LIBPATH:..\libs\glfw\lib-vc2010-32 glfw3.lib opengl32.lib gdi32.lib shell32.lib
-mkdir %OUT_DIR%
-cl /nologo /Zi /MD %INCLUDES% %SOURCES% /Fe%OUT_DIR%/%OUT_EXE%.exe /Fo%OUT_DIR%/ /link %LIBS%
+mkdir Debug
+cl /nologo /Zi /MD /I .. /I ..\.. /I ..\libs\glfw\include *.cpp ..\..\backends\imgui_impl_opengl2.cpp ..\..\backends\imgui_impl_glfw.cpp ..\..\imgui*.cpp /FeDebug/example_glfw_opengl2.exe /FoDebug/ /link /LIBPATH:..\libs\glfw\lib-vc2010-32 glfw3.lib opengl32.lib gdi32.lib shell32.lib

examples/example_glfw_opengl2/main.cpp

@@ -44,13 +44,25 @@ int main(int, char**)
     IMGUI_CHECKVERSION();
     ImGui::CreateContext();
     ImGuiIO& io = ImGui::GetIO(); (void)io;
-    //io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;     // Enable Keyboard Controls
+    io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;       // Enable Keyboard Controls
     //io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad;      // Enable Gamepad Controls
+    io.ConfigFlags |= ImGuiConfigFlags_DockingEnable;           // Enable Docking
+    io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable;         // Enable Multi-Viewport / Platform Windows
+    //io.ConfigViewportsNoAutoMerge = true;
+    //io.ConfigViewportsNoTaskBarIcon = true;
 
     // Setup Dear ImGui style
     ImGui::StyleColorsDark();
     //ImGui::StyleColorsClassic();
 
+    // When viewports are enabled we tweak WindowRounding/WindowBg so platform windows can look identical to regular ones.
+    ImGuiStyle& style = ImGui::GetStyle();
+    if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+    {
+        style.WindowRounding = 0.0f;
+        style.Colors[ImGuiCol_WindowBg].w = 1.0f;
+    }
+
     // Setup Platform/Renderer backends
     ImGui_ImplGlfw_InitForOpenGL(window, true);
     ImGui_ImplOpenGL2_Init();
@@ -136,14 +148,24 @@ int main(int, char**)
         glClear(GL_COLOR_BUFFER_BIT);
 
         // If you are using this code with non-legacy OpenGL header/contexts (which you should not, prefer using imgui_impl_opengl3.cpp!!),
-        // you may need to backup/reset/restore other state, e.g. for current shader using the commented lines below.
+        // you may need to backup/reset/restore current shader using the commented lines below.
         //GLint last_program;
         //glGetIntegerv(GL_CURRENT_PROGRAM, &last_program);
         //glUseProgram(0);
         ImGui_ImplOpenGL2_RenderDrawData(ImGui::GetDrawData());
         //glUseProgram(last_program);
 
-        glfwMakeContextCurrent(window);
+        // Update and Render additional Platform Windows
+        // (Platform functions may change the current OpenGL context, so we save/restore it to make it easier to paste this code elsewhere.
+        //  For this specific demo app we could also call glfwMakeContextCurrent(window) directly)
+        if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+        {
+            GLFWwindow* backup_current_context = glfwGetCurrentContext();
+            ImGui::UpdatePlatformWindows();
+            ImGui::RenderPlatformWindowsDefault();
+            glfwMakeContextCurrent(backup_current_context);
+        }
+
         glfwSwapBuffers(window);
     }
 

examples/example_glfw_opengl3/build_win32.bat

@@ -1,8 +1,3 @@
 @REM Build for Visual Studio compiler. Run your copy of vcvars32.bat or vcvarsall.bat to setup command-line compiler.
-@set OUT_DIR=Debug
-@set OUT_EXE=example_glfw_opengl3
-@set INCLUDES=/I..\.. /I..\..\backends /I..\libs\glfw\include /I..\libs\gl3w
-@set SOURCES=main.cpp ..\..\backends\imgui_impl_glfw.cpp ..\..\backends\imgui_impl_opengl3.cpp ..\..\imgui*.cpp ..\libs\gl3w\GL\gl3w.c 
-@set LIBS=/LIBPATH:..\libs\glfw\lib-vc2010-32 glfw3.lib opengl32.lib gdi32.lib shell32.lib
-mkdir %OUT_DIR%
-cl /nologo /Zi /MD %INCLUDES% %SOURCES% /Fe%OUT_DIR%/%OUT_EXE%.exe /Fo%OUT_DIR%/ /link %LIBS%
+mkdir Debug
+cl /nologo /Zi /MD /I .. /I ..\.. /I ..\libs\glfw\include /I ..\libs\gl3w *.cpp ..\..\backends\imgui_impl_glfw.cpp ..\..\backends\imgui_impl_opengl3.cpp ..\..\imgui*.cpp ..\libs\gl3w\GL\gl3w.c /FeDebug/example_glfw_opengl3.exe /FoDebug/ /link /LIBPATH:..\libs\glfw\lib-vc2010-32 glfw3.lib opengl32.lib gdi32.lib shell32.lib

examples/example_glfw_opengl3/main.cpp

@@ -108,13 +108,25 @@ int main(int, char**)
     IMGUI_CHECKVERSION();
     ImGui::CreateContext();
     ImGuiIO& io = ImGui::GetIO(); (void)io;
-    //io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;     // Enable Keyboard Controls
+    io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;       // Enable Keyboard Controls
     //io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad;      // Enable Gamepad Controls
+    io.ConfigFlags |= ImGuiConfigFlags_DockingEnable;           // Enable Docking
+    io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable;         // Enable Multi-Viewport / Platform Windows
+    //io.ConfigViewportsNoAutoMerge = true;
+    //io.ConfigViewportsNoTaskBarIcon = true;
 
     // Setup Dear ImGui style
     ImGui::StyleColorsDark();
     //ImGui::StyleColorsClassic();
 
+    // When viewports are enabled we tweak WindowRounding/WindowBg so platform windows can look identical to regular ones.
+    ImGuiStyle& style = ImGui::GetStyle();
+    if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+    {
+        style.WindowRounding = 0.0f;
+        style.Colors[ImGuiCol_WindowBg].w = 1.0f;
+    }
+
     // Setup Platform/Renderer backends
     ImGui_ImplGlfw_InitForOpenGL(window, true);
     ImGui_ImplOpenGL3_Init(glsl_version);
@@ -200,6 +212,17 @@ int main(int, char**)
         glClear(GL_COLOR_BUFFER_BIT);
         ImGui_ImplOpenGL3_RenderDrawData(ImGui::GetDrawData());
     	
+        // Update and Render additional Platform Windows
+        // (Platform functions may change the current OpenGL context, so we save/restore it to make it easier to paste this code elsewhere.
+        //  For this specific demo app we could also call glfwMakeContextCurrent(window) directly)
+        if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+        {
+            GLFWwindow* backup_current_context = glfwGetCurrentContext();
+            ImGui::UpdatePlatformWindows();
+            ImGui::RenderPlatformWindowsDefault();
+            glfwMakeContextCurrent(backup_current_context);
+        }
+
         glfwSwapBuffers(window);
     }
 

examples/example_glfw_vulkan/build_win32.bat

@@ -1,14 +1,7 @@
 @REM Build for Visual Studio compiler. Run your copy of vcvars32.bat or vcvarsall.bat to setup command-line compiler.
 
-@set OUT_EXE=example_glfw_vulkan
-@set INCLUDES=/I..\.. /I..\..\backends /I..\libs\glfw\include /I %VULKAN_SDK%\include
-@set SOURCES=main.cpp ..\..\backends\imgui_impl_vulkan.cpp ..\..\backends\imgui_impl_glfw.cpp ..\..\imgui*.cpp
-@set LIBS=/LIBPATH:..\libs\glfw\lib-vc2010-32 /libpath:%VULKAN_SDK%\lib32 glfw3.lib opengl32.lib gdi32.lib shell32.lib vulkan-1.lib
+mkdir Debug
+cl /nologo /Zi /MD /I .. /I ..\.. /I ..\libs\glfw\include /I %VULKAN_SDK%\include *.cpp ..\..\backends\imgui_impl_vulkan.cpp ..\..\backends\imgui_impl_glfw.cpp ..\..\imgui*.cpp /FeDebug/example_glfw_vulkan.exe /FoDebug/ /link /LIBPATH:..\libs\glfw\lib-vc2010-32 /libpath:%VULKAN_SDK%\lib32 glfw3.lib opengl32.lib gdi32.lib shell32.lib vulkan-1.lib
 
-@set OUT_DIR=Debug
-mkdir %OUT_DIR%
-cl /nologo /Zi /MD %INCLUDES% %SOURCES% /Fe%OUT_DIR%/%OUT_EXE%.exe /Fo%OUT_DIR%/ /link %LIBS%
-
-@set OUT_DIR=Release
-mkdir %OUT_DIR%
-cl /nologo /Zi /MD /Ox /Oi %INCLUDES% %SOURCES% /Fe%OUT_DIR%/%OUT_EXE%.exe /Fo%OUT_DIR%/ /link %LIBS%
+mkdir Release
+cl /nologo /Zi /MD /Ox /Oi /I .. /I ..\.. /I ..\libs\glfw\include /I %VULKAN_SDK%\include *.cpp ..\..\backends\imgui_impl_vulkan.cpp ..\..\backends\imgui_impl_glfw.cpp ..\..\imgui*.cpp /FeRelease/example_glfw_vulkan.exe /FoRelease/ /link /LIBPATH:..\libs\glfw\lib-vc2010-32 /libpath:%VULKAN_SDK%\lib32 glfw3.lib opengl32.lib gdi32.lib shell32.lib vulkan-1.lib

examples/example_glfw_vulkan/build_win64.bat

@@ -1,13 +1,7 @@
 @REM Build for Visual Studio compiler. Run your copy of amd64/vcvars32.bat to setup 64-bit command-line compiler.
 
-@set INCLUDES=/I..\.. /I..\..\backends /I..\libs\glfw\include /I %VULKAN_SDK%\include
-@set SOURCES=main.cpp ..\..\backends\imgui_impl_vulkan.cpp ..\..\backends\imgui_impl_glfw.cpp ..\..\imgui*.cpp
-@set LIBS=/LIBPATH:..\libs\glfw\lib-vc2010-64 /libpath:%VULKAN_SDK%\lib glfw3.lib opengl32.lib gdi32.lib shell32.lib vulkan-1.lib
+mkdir Debug
+cl /nologo /Zi /MD /I .. /I ..\.. /I ..\libs\glfw\include /I %VULKAN_SDK%\include *.cpp ..\..\backends\imgui_impl_vulkan.cpp ..\..\backends\imgui_impl_glfw.cpp ..\..\imgui*.cpp /FeDebug/example_glfw_vulkan.exe /FoDebug/ /link /LIBPATH:..\libs\glfw\lib-vc2010-64 /libpath:%VULKAN_SDK%\lib glfw3.lib opengl32.lib gdi32.lib shell32.lib vulkan-1.lib
 
-@set OUT_DIR=Debug
-mkdir %OUT_DIR%
-cl /nologo /Zi /MD %INCLUDES% %SOURCES% /Fe%OUT_DIR%/%OUT_EXE%.exe /Fo%OUT_DIR%/ /link %LIBS%
-
-@set OUT_DIR=Release
-mkdir %OUT_DIR%
-cl /nologo /Zi /MD /Ox /Oi %INCLUDES% %SOURCES% /Fe%OUT_DIR%/%OUT_EXE%.exe /Fo%OUT_DIR%/ /link %LIBS%
+mkdir Release
+cl /nologo /Zi /MD /Ox /Oi /I .. /I ..\.. /I ..\libs\glfw\include /I %VULKAN_SDK%\include *.cpp ..\..\backends\imgui_impl_vulkan.cpp ..\..\backends\imgui_impl_glfw.cpp ..\..\imgui*.cpp /FeRelease/example_glfw_vulkan.exe /FoRelease/ /link /LIBPATH:..\libs\glfw\lib-vc2010-64 /libpath:%VULKAN_SDK%\lib glfw3.lib opengl32.lib gdi32.lib shell32.lib vulkan-1.lib

examples/example_glfw_vulkan/main.cpp

@@ -375,13 +375,25 @@ int main(int, char**)
     IMGUI_CHECKVERSION();
     ImGui::CreateContext();
     ImGuiIO& io = ImGui::GetIO(); (void)io;
-    //io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;     // Enable Keyboard Controls
+    io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;       // Enable Keyboard Controls
     //io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad;      // Enable Gamepad Controls
+    io.ConfigFlags |= ImGuiConfigFlags_DockingEnable;           // Enable Docking
+    io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable;         // Enable Multi-Viewport / Platform Windows
+    //io.ConfigViewportsNoAutoMerge = true;
+    //io.ConfigViewportsNoTaskBarIcon = true;
 
     // Setup Dear ImGui style
     ImGui::StyleColorsDark();
     //ImGui::StyleColorsClassic();
 
+    // When viewports are enabled we tweak WindowRounding/WindowBg so platform windows can look identical to regular ones.
+    ImGuiStyle& style = ImGui::GetStyle();
+    if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+    {
+        style.WindowRounding = 0.0f;
+        style.Colors[ImGuiCol_WindowBg].w = 1.0f;
+    }
+
     // Setup Platform/Renderer backends
     ImGui_ImplGlfw_InitForVulkan(window, true);
     ImGui_ImplVulkan_InitInfo init_info = {};
@@ -516,14 +528,22 @@ int main(int, char**)
 
         // Rendering
         ImGui::Render();
-        ImDrawData* draw_data = ImGui::GetDrawData();
-        const bool is_minimized = (draw_data->DisplaySize.x <= 0.0f || draw_data->DisplaySize.y <= 0.0f);
-        if (!is_minimized)
-        {
+        ImDrawData* main_draw_data = ImGui::GetDrawData();
+        const bool main_is_minimized = (main_draw_data->DisplaySize.x <= 0.0f || main_draw_data->DisplaySize.y <= 0.0f);
         memcpy(&wd->ClearValue.color.float32[0], &clear_color, 4 * sizeof(float));
-            FrameRender(wd, draw_data);
-            FramePresent(wd);
+        if (!main_is_minimized)
+            FrameRender(wd, main_draw_data);
+
+        // Update and Render additional Platform Windows
+        if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+        {
+            ImGui::UpdatePlatformWindows();
+            ImGui::RenderPlatformWindowsDefault();
         }
+
+        // Present Main Platform Window
+        if (!main_is_minimized)
+            FramePresent(wd);
     }
 
     // Cleanup

examples/example_glut_opengl2/main.cpp

@@ -2,8 +2,8 @@
 // If you are new to Dear ImGui, read documentation from the docs/ folder + read the top of imgui.cpp.
 // Read online: https://github.com/ocornut/imgui/tree/master/docs
 
-// !!! GLUT/FreeGLUT IS OBSOLETE PREHISTORIC SOFTWARE. Using GLUT is not recommended unless you really miss the 90's. !!!
-// !!! If someone or something is teaching you GLUT today, you are being abused. Please show some resistance. !!!
+// !!! GLUT/FreeGLUT IS OBSOLETE SOFTWARE. Using GLUT is not recommended unless you really miss the 90's. !!!
+// !!! If someone or something is teaching you GLUT in 2020, you are being abused. Please show some resistance. !!!
 // !!! Nowadays, prefer using GLFW or SDL instead!
 
 #include "imgui.h"
@@ -111,6 +111,7 @@ int main(int argc, char** argv)
     ImGui::CreateContext();
     ImGuiIO& io = ImGui::GetIO(); (void)io;
     //io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;     // Enable Keyboard Controls
+    io.ConfigFlags |= ImGuiConfigFlags_DockingEnable;           // Enable Docking
 
     // Setup Dear ImGui style
     ImGui::StyleColorsDark();

examples/example_marmalade/main.cpp

@@ -22,6 +22,7 @@ int main(int, char**)
     ImGui::CreateContext();
     ImGuiIO& io = ImGui::GetIO(); (void)io;
     //io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;  // Enable Keyboard Controls
+    io.ConfigFlags |= ImGuiConfigFlags_DockingEnable;        // Enable Docking
 
     // Setup Dear ImGui style
     ImGui::StyleColorsDark();

examples/example_sdl_directx11/build_win32.bat

@@ -1,8 +1,8 @@
 @REM Build for Visual Studio compiler. Run your copy of vcvars32.bat or vcvarsall.bat to setup command-line compiler.
-@set OUT_DIR=Debug
-@set OUT_EXE=example_sdl_directx11
-@set INCLUDES=/I..\.. /I..\..\backends /I%SDL2_DIR%\include /I "%WindowsSdkDir%Include\um" /I "%WindowsSdkDir%Include\shared" /I "%DXSDK_DIR%Include"
-@set SOURCES=main.cpp ..\..\backends\imgui_impl_sdl.cpp ..\..\backends\imgui_impl_dx11.cpp ..\..\imgui*.cpp
-@set LIBS=/LIBPATH:%SDL2_DIR%\lib\x86 SDL2.lib SDL2main.lib /LIBPATH:"%DXSDK_DIR%/Lib/x86" d3d11.lib d3dcompiler.lib
+set OUT_DIR=Debug
+set OUT_EXE=example_sdl_directx11
+set INCLUDES=/I.. /I..\.. /I%SDL2_DIR%\include /I "%WindowsSdkDir%Include\um" /I "%WindowsSdkDir%Include\shared" /I "%DXSDK_DIR%Include"
+set SOURCES=main.cpp ..\..\backends\imgui_impl_sdl.cpp ..\..\backends\imgui_impl_dx11.cpp ..\..\imgui*.cpp
+set LIBS=/libpath:%SDL2_DIR%\lib\x86 SDL2.lib SDL2main.lib /LIBPATH:"%DXSDK_DIR%/Lib/x86" d3d11.lib d3dcompiler.lib
 mkdir %OUT_DIR%
 cl /nologo /Zi /MD %INCLUDES% %SOURCES% /Fe%OUT_DIR%/%OUT_EXE%.exe /Fo%OUT_DIR%/ /link %LIBS% /subsystem:console

examples/example_sdl_directx11/main.cpp

@@ -54,13 +54,25 @@ int main(int, char**)
     IMGUI_CHECKVERSION();
     ImGui::CreateContext();
     ImGuiIO& io = ImGui::GetIO(); (void)io;
-    //io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;     // Enable Keyboard Controls
+    io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;       // Enable Keyboard Controls
     //io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad;      // Enable Gamepad Controls
+    io.ConfigFlags |= ImGuiConfigFlags_DockingEnable;           // Enable Docking
+    io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable;         // Enable Multi-Viewport / Platform Windows
+    //io.ConfigViewportsNoAutoMerge = true;
+    //io.ConfigViewportsNoTaskBarIcon = true;
 
     // Setup Dear ImGui style
     ImGui::StyleColorsDark();
     //ImGui::StyleColorsClassic();
 
+    // When viewports are enabled we tweak WindowRounding/WindowBg so platform windows can look identical to regular ones.
+    ImGuiStyle& style = ImGui::GetStyle();
+    if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+    {
+        style.WindowRounding = 0.0f;
+        style.Colors[ImGuiCol_WindowBg].w = 1.0f;
+    }
+
     // Setup Platform/Renderer backends
     ImGui_ImplSDL2_InitForD3D(window);
     ImGui_ImplDX11_Init(g_pd3dDevice, g_pd3dDeviceContext);
@@ -159,6 +171,13 @@ int main(int, char**)
         g_pd3dDeviceContext->ClearRenderTargetView(g_mainRenderTargetView, (float*)&clear_color);
         ImGui_ImplDX11_RenderDrawData(ImGui::GetDrawData());
 
+        // Update and Render additional Platform Windows
+        if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+        {
+            ImGui::UpdatePlatformWindows();
+            ImGui::RenderPlatformWindowsDefault();
+        }
+
         g_pSwapChain->Present(1, 0); // Present with vsync
         //g_pSwapChain->Present(0, 0); // Present without vsync
     }

examples/example_sdl_opengl2/build_win32.bat

@@ -1,8 +1,8 @@
 @REM Build for Visual Studio compiler. Run your copy of vcvars32.bat or vcvarsall.bat to setup command-line compiler.
-@set OUT_DIR=Debug
-@set OUT_EXE=example_sdl_opengl2
-@set INCLUDES=/I..\.. /I..\..\backends /I%SDL2_DIR%\include
-@set SOURCES=main.cpp ..\..\backends\imgui_impl_sdl.cpp ..\..\backends\imgui_impl_opengl2.cpp ..\..\imgui*.cpp
-@set LIBS=/LIBPATH:%SDL2_DIR%\lib\x86 SDL2.lib SDL2main.lib opengl32.lib
+set OUT_DIR=Debug
+set OUT_EXE=example_sdl_opengl2
+set INCLUDES=/I.. /I..\.. /I%SDL2_DIR%\include
+set SOURCES=main.cpp ..\..\backends\imgui_impl_sdl.cpp ..\..\backends\imgui_impl_opengl2.cpp ..\..\imgui*.cpp
+set LIBS=/libpath:%SDL2_DIR%\lib\x86 SDL2.lib SDL2main.lib opengl32.lib
 mkdir %OUT_DIR%
 cl /nologo /Zi /MD %INCLUDES% %SOURCES% /Fe%OUT_DIR%/%OUT_EXE%.exe /Fo%OUT_DIR%/ /link %LIBS% /subsystem:console

examples/example_sdl_opengl2/main.cpp

@@ -42,13 +42,25 @@ int main(int, char**)
     IMGUI_CHECKVERSION();
     ImGui::CreateContext();
     ImGuiIO& io = ImGui::GetIO(); (void)io;
-    //io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;     // Enable Keyboard Controls
+    io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;       // Enable Keyboard Controls
     //io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad;      // Enable Gamepad Controls
+    io.ConfigFlags |= ImGuiConfigFlags_DockingEnable;           // Enable Docking
+    io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable;         // Enable Multi-Viewport / Platform Windows
+    //io.ConfigViewportsNoAutoMerge = true;
+    //io.ConfigViewportsNoTaskBarIcon = true;
 
     // Setup Dear ImGui style
     ImGui::StyleColorsDark();
     //ImGui::StyleColorsClassic();
 
+    // When viewports are enabled we tweak WindowRounding/WindowBg so platform windows can look identical to regular ones.
+    ImGuiStyle& style = ImGui::GetStyle();
+    if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+    {
+        style.WindowRounding = 0.0f;
+        style.Colors[ImGuiCol_WindowBg].w = 1.0f;
+    }
+
     // Setup Platform/Renderer backends
     ImGui_ImplSDL2_InitForOpenGL(window, gl_context);
     ImGui_ImplOpenGL2_Init();
@@ -141,6 +153,19 @@ int main(int, char**)
         glClear(GL_COLOR_BUFFER_BIT);
         //glUseProgram(0); // You may want this if using this code in an OpenGL 3+ context where shaders may be bound
         ImGui_ImplOpenGL2_RenderDrawData(ImGui::GetDrawData());
+
+        // Update and Render additional Platform Windows
+        // (Platform functions may change the current OpenGL context, so we save/restore it to make it easier to paste this code elsewhere.
+        //  For this specific demo app we could also call SDL_GL_MakeCurrent(window, gl_context) directly)
+        if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+        {
+            SDL_Window* backup_current_window = SDL_GL_GetCurrentWindow();
+            SDL_GLContext backup_current_context = SDL_GL_GetCurrentContext();
+            ImGui::UpdatePlatformWindows();
+            ImGui::RenderPlatformWindowsDefault();
+            SDL_GL_MakeCurrent(backup_current_window, backup_current_context);
+        }
+
         SDL_GL_SwapWindow(window);
     }
 

examples/example_sdl_opengl3/build_win32.bat

@@ -1,8 +1,8 @@
 @REM Build for Visual Studio compiler. Run your copy of vcvars32.bat or vcvarsall.bat to setup command-line compiler.
-@set OUT_DIR=Debug
-@set OUT_EXE=example_sdl_opengl3
-@set INCLUDES=/I..\.. /I..\..\backends /I%SDL2_DIR%\include /I..\libs\gl3w
-@set SOURCES=main.cpp ..\..\backends\imgui_impl_sdl.cpp ..\..\backends\imgui_impl_opengl3.cpp ..\..\imgui*.cpp ..\libs\gl3w\GL\gl3w.c
-@set LIBS=/LIBPATH:%SDL2_DIR%\lib\x86 SDL2.lib SDL2main.lib opengl32.lib
+set OUT_DIR=Debug
+set OUT_EXE=example_sdl_opengl3
+set INCLUDES=/I.. /I..\.. /I%SDL2_DIR%\include /I..\libs\gl3w
+set SOURCES=main.cpp ..\..\backends\imgui_impl_sdl.cpp ..\..\backends\imgui_impl_opengl3.cpp ..\..\imgui*.cpp ..\libs\gl3w\GL\gl3w.c
+set LIBS=/libpath:%SDL2_DIR%\lib\x86 SDL2.lib SDL2main.lib opengl32.lib
 mkdir %OUT_DIR%
 cl /nologo /Zi /MD %INCLUDES% %SOURCES% /Fe%OUT_DIR%/%OUT_EXE%.exe /Fo%OUT_DIR%/ /link %LIBS% /subsystem:console

examples/example_sdl_opengl3/main.cpp

@@ -103,13 +103,25 @@ int main(int, char**)
     IMGUI_CHECKVERSION();
     ImGui::CreateContext();
     ImGuiIO& io = ImGui::GetIO(); (void)io;
-    //io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;     // Enable Keyboard Controls
+    io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;       // Enable Keyboard Controls
     //io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad;      // Enable Gamepad Controls
+    io.ConfigFlags |= ImGuiConfigFlags_DockingEnable;           // Enable Docking
+    io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable;         // Enable Multi-Viewport / Platform Windows
+    //io.ConfigViewportsNoAutoMerge = true;
+    //io.ConfigViewportsNoTaskBarIcon = true;
 
     // Setup Dear ImGui style
     ImGui::StyleColorsDark();
     //ImGui::StyleColorsClassic();
 
+    // When viewports are enabled we tweak WindowRounding/WindowBg so platform windows can look identical to regular ones.
+    ImGuiStyle& style = ImGui::GetStyle();
+    if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+    {
+        style.WindowRounding = 0.0f;
+        style.Colors[ImGuiCol_WindowBg].w = 1.0f;
+    }
+
     // Setup Platform/Renderer backends
     ImGui_ImplSDL2_InitForOpenGL(window, gl_context);
     ImGui_ImplOpenGL3_Init(glsl_version);
@@ -201,6 +213,19 @@ int main(int, char**)
         glClearColor(clear_color.x, clear_color.y, clear_color.z, clear_color.w);
         glClear(GL_COLOR_BUFFER_BIT);
         ImGui_ImplOpenGL3_RenderDrawData(ImGui::GetDrawData());
+
+        // Update and Render additional Platform Windows
+        // (Platform functions may change the current OpenGL context, so we save/restore it to make it easier to paste this code elsewhere.
+        //  For this specific demo app we could also call SDL_GL_MakeCurrent(window, gl_context) directly)
+        if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+        {
+            SDL_Window* backup_current_window = SDL_GL_GetCurrentWindow();
+            SDL_GLContext backup_current_context = SDL_GL_GetCurrentContext();
+            ImGui::UpdatePlatformWindows();
+            ImGui::RenderPlatformWindowsDefault();
+            SDL_GL_MakeCurrent(backup_current_window, backup_current_context);
+        }
+
         SDL_GL_SwapWindow(window);
     }
 

examples/example_sdl_vulkan/main.cpp

@@ -367,13 +367,25 @@ int main(int, char**)
     IMGUI_CHECKVERSION();
     ImGui::CreateContext();
     ImGuiIO& io = ImGui::GetIO(); (void)io;
-    //io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;     // Enable Keyboard Controls
+    io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;       // Enable Keyboard Controls
     //io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad;      // Enable Gamepad Controls
+    io.ConfigFlags |= ImGuiConfigFlags_DockingEnable;           // Enable Docking
+    io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable;         // Enable Multi-Viewport / Platform Windows
+    //io.ConfigFlags |= ImGuiConfigFlags_ViewportsNoTaskBarIcons;
+    //io.ConfigFlags |= ImGuiConfigFlags_ViewportsNoMerge;
 
     // Setup Dear ImGui style
     ImGui::StyleColorsDark();
     //ImGui::StyleColorsClassic();
 
+    // When viewports are enabled we tweak WindowRounding/WindowBg so platform windows can look identical to regular ones.
+    ImGuiStyle& style = ImGui::GetStyle();
+    if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+    {
+        style.WindowRounding = 0.0f;
+        style.Colors[ImGuiCol_WindowBg].w = 1.0f;
+    }
+
     // Setup Platform/Renderer backends
     ImGui_ImplSDL2_InitForVulkan(window);
     ImGui_ImplVulkan_InitInfo init_info = {};
@@ -517,14 +529,22 @@ int main(int, char**)
 
         // Rendering
         ImGui::Render();
-        ImDrawData* draw_data = ImGui::GetDrawData();
-        const bool is_minimized = (draw_data->DisplaySize.x <= 0.0f || draw_data->DisplaySize.y <= 0.0f);
-        if (!is_minimized)
-        {
+        ImDrawData* main_draw_data = ImGui::GetDrawData();
+        const bool main_is_minimized = (main_draw_data->DisplaySize.x <= 0.0f || main_draw_data->DisplaySize.y <= 0.0f);
         memcpy(&wd->ClearValue.color.float32[0], &clear_color, 4 * sizeof(float));
-            FrameRender(wd, draw_data);
-            FramePresent(wd);
+        if (!main_is_minimized)
+            FrameRender(wd, main_draw_data);
+
+        // Update and Render additional Platform Windows
+        if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+        {
+            ImGui::UpdatePlatformWindows();
+            ImGui::RenderPlatformWindowsDefault();
         }
+
+        // Present Main Platform Window
+        if (!main_is_minimized)
+            FramePresent(wd);
     }
 
     // Cleanup

examples/example_win32_directx10/build_win32.bat

@@ -1,8 +1,4 @@
 @REM Build for Visual Studio compiler. Run your copy of vcvars32.bat or vcvarsall.bat to setup command-line compiler.
-@set OUT_DIR=Debug
-@set OUT_EXE=example_win32_directx10
-@set INCLUDES=/I..\.. /I..\..\backends /I "%WindowsSdkDir%Include\um" /I "%WindowsSdkDir%Include\shared" /I "%DXSDK_DIR%Include"
-@set SOURCES=main.cpp ..\..\backends\imgui_impl_win32.cpp ..\..\backends\imgui_impl_dx10.cpp ..\..\imgui*.cpp
-@set LIBS=/LIBPATH:"%DXSDK_DIR%/Lib/x86" d3d10.lib d3dcompiler.lib
-mkdir %OUT_DIR%
-cl /nologo /Zi /MD %INCLUDES% /D UNICODE /D _UNICODE %SOURCES% /Fe%OUT_DIR%/%OUT_EXE%.exe /Fo%OUT_DIR%/ /link %LIBS%
+mkdir Debug
+cl /nologo /Zi /MD /I .. /I ..\.. /I "%WindowsSdkDir%Include\um" /I "%WindowsSdkDir%Include\shared" /I "%DXSDK_DIR%Include" /D UNICODE /D _UNICODE *.cpp ..\..\backends\imgui_impl_win32.cpp ..\..\backends\imgui_impl_dx10.cpp ..\..\imgui*.cpp /FeDebug/example_win32_directx10.exe /FoDebug/ /link /LIBPATH:"%DXSDK_DIR%/Lib/x86" d3d10.lib d3dcompiler.lib
+

examples/example_win32_directx10/main.cpp

@@ -26,6 +26,8 @@ LRESULT WINAPI WndProc(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam);
 // Main code
 int main(int, char**)
 {
+    ImGui_ImplWin32_EnableDpiAwareness();
+
     // Create application window
     //ImGui_ImplWin32_EnableDpiAwareness();
     WNDCLASSEX wc = { sizeof(WNDCLASSEX), CS_CLASSDC, WndProc, 0L, 0L, GetModuleHandle(NULL), NULL, NULL, NULL, NULL, _T("ImGui Example"), NULL };
@@ -48,13 +50,25 @@ int main(int, char**)
     IMGUI_CHECKVERSION();
     ImGui::CreateContext();
     ImGuiIO& io = ImGui::GetIO(); (void)io;
-    //io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;     // Enable Keyboard Controls
+    io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;       // Enable Keyboard Controls
     //io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad;      // Enable Gamepad Controls
+    io.ConfigFlags |= ImGuiConfigFlags_DockingEnable;           // Enable Docking
+    io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable;         // Enable Multi-Viewport / Platform Windows
+    //io.ConfigViewportsNoAutoMerge = true;
+    //io.ConfigViewportsNoTaskBarIcon = true;
 
     // Setup Dear ImGui style
     ImGui::StyleColorsDark();
     //ImGui::StyleColorsClassic();
 
+    // When viewports are enabled we tweak WindowRounding/WindowBg so platform windows can look identical to regular ones.
+    ImGuiStyle& style = ImGui::GetStyle();
+    if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+    {
+        style.WindowRounding = 0.0f;
+        style.Colors[ImGuiCol_WindowBg].w = 1.0f;
+    }
+
     // Setup Platform/Renderer backends
     ImGui_ImplWin32_Init(hwnd);
     ImGui_ImplDX10_Init(g_pd3dDevice);
@@ -144,6 +158,13 @@ int main(int, char**)
         g_pd3dDevice->ClearRenderTargetView(g_mainRenderTargetView, (float*)&clear_color);
         ImGui_ImplDX10_RenderDrawData(ImGui::GetDrawData());
 
+        // Update and Render additional Platform Windows
+        if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+        {
+            ImGui::UpdatePlatformWindows();
+            ImGui::RenderPlatformWindowsDefault();
+        }
+
         g_pSwapChain->Present(1, 0); // Present with vsync
         //g_pSwapChain->Present(0, 0); // Present without vsync
     }

examples/example_win32_directx11/build_win32.bat

@@ -1,9 +1,4 @@
 @REM Build for Visual Studio compiler. Run your copy of vcvars32.bat or vcvarsall.bat to setup command-line compiler.
-@set OUT_DIR=Debug
-@set OUT_EXE=example_win32_directx11
-@set INCLUDES=/I..\.. /I..\..\backends /I "%WindowsSdkDir%Include\um" /I "%WindowsSdkDir%Include\shared" /I "%DXSDK_DIR%Include"
-@set SOURCES=main.cpp ..\..\backends\imgui_impl_dx11.cpp ..\..\backends\imgui_impl_win32.cpp ..\..\imgui*.cpp
-@set LIBS=/LIBPATH:"%DXSDK_DIR%/Lib/x86" d3d11.lib d3dcompiler.lib
-mkdir %OUT_DIR%
-cl /nologo /Zi /MD %INCLUDES% /D UNICODE /D _UNICODE %SOURCES% /Fe%OUT_DIR%/%OUT_EXE%.exe /Fo%OUT_DIR%/ /link %LIBS%
+mkdir Debug
+cl /nologo /Zi /MD /I .. /I ..\.. /I "%WindowsSdkDir%Include\um" /I "%WindowsSdkDir%Include\shared" /I "%DXSDK_DIR%Include" /D UNICODE /D _UNICODE *.cpp ..\..\backends\imgui_impl_dx11.cpp ..\..\backends\imgui_impl_win32.cpp ..\..\imgui*.cpp /FeDebug/example_win32_directx11.exe /FoDebug/ /link /LIBPATH:"%DXSDK_DIR%/Lib/x86" d3d11.lib d3dcompiler.lib
 

examples/example_win32_directx11/main.cpp

@@ -26,6 +26,8 @@ LRESULT WINAPI WndProc(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam);
 // Main code
 int main(int, char**)
 {
+    ImGui_ImplWin32_EnableDpiAwareness();
+
     // Create application window
     //ImGui_ImplWin32_EnableDpiAwareness();
     WNDCLASSEX wc = { sizeof(WNDCLASSEX), CS_CLASSDC, WndProc, 0L, 0L, GetModuleHandle(NULL), NULL, NULL, NULL, NULL, _T("ImGui Example"), NULL };
@@ -48,13 +50,32 @@ int main(int, char**)
     IMGUI_CHECKVERSION();
     ImGui::CreateContext();
     ImGuiIO& io = ImGui::GetIO(); (void)io;
-    //io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;     // Enable Keyboard Controls
+    io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;       // Enable Keyboard Controls
     //io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad;      // Enable Gamepad Controls
+    io.ConfigFlags |= ImGuiConfigFlags_DockingEnable;           // Enable Docking
+    io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable;         // Enable Multi-Viewport / Platform Windows
+    //io.ConfigViewportsNoAutoMerge = true;
+    //io.ConfigViewportsNoTaskBarIcon = true;
+    //io.ConfigViewportsNoDefaultParent = true;
+    //io.ConfigDockingAlwaysTabBar = true;
+    //io.ConfigDockingTransparentPayload = true;
+#if 1
+    io.ConfigFlags |= ImGuiConfigFlags_DpiEnableScaleFonts;     // FIXME-DPI: THIS CURRENTLY DOESN'T WORK AS EXPECTED. DON'T USE IN USER APP!
+    io.ConfigFlags |= ImGuiConfigFlags_DpiEnableScaleViewports; // FIXME-DPI
+#endif
 
     // Setup Dear ImGui style
     ImGui::StyleColorsDark();
     //ImGui::StyleColorsClassic();
 
+    // When viewports are enabled we tweak WindowRounding/WindowBg so platform windows can look identical to regular ones.
+    ImGuiStyle& style = ImGui::GetStyle();
+    if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+    {
+        style.WindowRounding = 0.0f;
+        style.Colors[ImGuiCol_WindowBg].w = 1.0f;
+    }
+
     // Setup Platform/Renderer backends
     ImGui_ImplWin32_Init(hwnd);
     ImGui_ImplDX11_Init(g_pd3dDevice, g_pd3dDeviceContext);
@@ -101,17 +122,21 @@ int main(int, char**)
         ImGui_ImplWin32_NewFrame();
         ImGui::NewFrame();
 
+#if 1
+        // Enable Debugging
+        io.ConfigDebugBeginReturnValue = io.KeyShift;
+#endif
+
         // 1. Show the big demo window (Most of the sample code is in ImGui::ShowDemoWindow()! You can browse its code to learn more about Dear ImGui!).
         if (show_demo_window)
             ImGui::ShowDemoWindow(&show_demo_window);
 
         // 2. Show a simple window that we create ourselves. We use a Begin/End pair to created a named window.
+        if (ImGui::Begin("Hello, world!"))                          // Create a window called "Hello, world!" and append into it.
         {
             static float f = 0.0f;
             static int counter = 0;
 
-            ImGui::Begin("Hello, world!");                          // Create a window called "Hello, world!" and append into it.
-
             ImGui::Text("This is some useful text.");               // Display some text (you can use a format strings too)
             ImGui::Checkbox("Demo Window", &show_demo_window);      // Edit bools storing our window open/close state
             ImGui::Checkbox("Another Window", &show_another_window);
@@ -129,9 +154,9 @@ int main(int, char**)
         }
 
         // 3. Show another simple window.
-        if (show_another_window)
+        // Passing a pointer to our bool variable in the Begin() call: the window will have a closing button that will clear the bool when clicked.
+        if (show_another_window && ImGui::Begin("Another Window", &show_another_window))
         {
-            ImGui::Begin("Another Window", &show_another_window);   // Pass a pointer to our bool variable (the window will have a closing button that will clear the bool when clicked)
             ImGui::Text("Hello from another window!");
             if (ImGui::Button("Close Me"))
                 show_another_window = false;
@@ -144,6 +169,13 @@ int main(int, char**)
         g_pd3dDeviceContext->ClearRenderTargetView(g_mainRenderTargetView, (float*)&clear_color);
         ImGui_ImplDX11_RenderDrawData(ImGui::GetDrawData());
 
+        // Update and Render additional Platform Windows
+        if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+        {
+            ImGui::UpdatePlatformWindows();
+            ImGui::RenderPlatformWindowsDefault();
+        }
+
         g_pSwapChain->Present(1, 0); // Present with vsync
         //g_pSwapChain->Present(0, 0); // Present without vsync
     }
@@ -213,6 +245,10 @@ void CleanupRenderTarget()
     if (g_mainRenderTargetView) { g_mainRenderTargetView->Release(); g_mainRenderTargetView = NULL; }
 }
 
+#ifndef WM_DPICHANGED
+#define WM_DPICHANGED 0x02E0 // From Windows SDK 8.1+ headers
+#endif
+
 // Forward declare message handler from imgui_impl_win32.cpp
 extern IMGUI_IMPL_API LRESULT ImGui_ImplWin32_WndProcHandler(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam);
 
@@ -239,6 +275,15 @@ LRESULT WINAPI WndProc(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam)
     case WM_DESTROY:
         ::PostQuitMessage(0);
         return 0;
+    case WM_DPICHANGED:
+        if (ImGui::GetIO().ConfigFlags & ImGuiConfigFlags_DpiEnableScaleViewports)
+        {
+            //const int dpi = HIWORD(wParam);
+            //printf("WM_DPICHANGED to %d (%.0f%%)\n", dpi, (float)dpi / 96.0f * 100.0f);
+            const RECT* suggested_rect = (RECT*)lParam;
+            ::SetWindowPos(hWnd, NULL, suggested_rect->left, suggested_rect->top, suggested_rect->right - suggested_rect->left, suggested_rect->bottom - suggested_rect->top, SWP_NOZORDER | SWP_NOACTIVATE);
+        }
+        break;
     }
     return ::DefWindowProc(hWnd, msg, wParam, lParam);
 }

examples/example_win32_directx12/build_win32.bat

@@ -1,9 +1,5 @@
 @REM Build for Visual Studio compiler. Run your copy of vcvars32.bat or vcvarsall.bat to setup command-line compiler.
 @REM Important: to build on 32-bit systems, the DX12 backends needs '#define ImTextureID ImU64', so we pass it here.
-@set OUT_DIR=Debug
-@set OUT_EXE=example_win32_directx12
-@set INCLUDES=/I..\.. /I..\..\backends /I "%WindowsSdkDir%Include\um" /I "%WindowsSdkDir%Include\shared"
-@set SOURCES=main.cpp ..\..\backends\imgui_impl_dx12.cpp ..\..\backends\imgui_impl_win32.cpp ..\..\imgui*.cpp
-@set LIBS=d3d12.lib d3dcompiler.lib dxgi.lib
 mkdir Debug
-cl /nologo /Zi /MD %INCLUDES% /D ImTextureID=ImU64 /D UNICODE /D _UNICODE %SOURCES% /Fe%OUT_DIR%/%OUT_EXE%.exe /Fo%OUT_DIR%/ /link %LIBS%
+cl /nologo /Zi /MD /I .. /I ..\.. /I "%WindowsSdkDir%Include\um" /I "%WindowsSdkDir%Include\shared" /D ImTextureID=ImU64 /D UNICODE /D _UNICODE *.cpp ..\..\backends\imgui_impl_dx12.cpp ..\..\backends\imgui_impl_win32.cpp ..\..\imgui*.cpp /FeDebug/example_win32_directx12.exe /FoDebug/ /link d3d12.lib d3dcompiler.lib dxgi.lib
+

examples/example_win32_directx12/main.cpp

@@ -1,10 +1,7 @@
 // Dear ImGui: standalone example application for DirectX 12
 // If you are new to Dear ImGui, read documentation from the docs/ folder + read the top of imgui.cpp.
 // Read online: https://github.com/ocornut/imgui/tree/master/docs
-
-// Important: to compile on 32-bit systems, the DirectX12 backend requires code to be compiled with '#define ImTextureID ImU64'.
-// This is because we need ImTextureID to carry a 64-bit value and by default ImTextureID is defined as void*.
-// This define is set in the example .vcxproj file and need to be replicated in your app or by adding it to your imconfig.h file.
+// FIXME: 64-bit only for now! (Because sizeof(ImTextureId) == sizeof(void*))
 
 #include "imgui.h"
 #include "imgui_impl_win32.h"
@@ -82,13 +79,25 @@ int main(int, char**)
     IMGUI_CHECKVERSION();
     ImGui::CreateContext();
     ImGuiIO& io = ImGui::GetIO(); (void)io;
-    //io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;     // Enable Keyboard Controls
+    io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;       // Enable Keyboard Controls
     //io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad;      // Enable Gamepad Controls
+    io.ConfigFlags |= ImGuiConfigFlags_DockingEnable;           // Enable Docking
+    io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable;         // Enable Multi-Viewport / Platform Windows
+    //io.ConfigViewportsNoAutoMerge = true;
+    //io.ConfigViewportsNoTaskBarIcon = true;
 
     // Setup Dear ImGui style
     ImGui::StyleColorsDark();
     //ImGui::StyleColorsClassic();
 
+    // When viewports are enabled we tweak WindowRounding/WindowBg so platform windows can look identical to regular ones.
+    ImGuiStyle& style = ImGui::GetStyle();
+    if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+    {
+        style.WindowRounding = 0.0f;
+        style.Colors[ImGuiCol_WindowBg].w = 1.0f;
+    }
+
     // Setup Platform/Renderer backends
     ImGui_ImplWin32_Init(hwnd);
     ImGui_ImplDX12_Init(g_pd3dDevice, NUM_FRAMES_IN_FLIGHT,
@@ -176,11 +185,9 @@ int main(int, char**)
         }
 
         // Rendering
-        ImGui::Render();
-
-        FrameContext* frameCtx = WaitForNextFrameResources();
+        FrameContext* frameCtxt = WaitForNextFrameResources();
         UINT backBufferIdx = g_pSwapChain->GetCurrentBackBufferIndex();
-        frameCtx->CommandAllocator->Reset();
+        frameCtxt->CommandAllocator->Reset();
 
         D3D12_RESOURCE_BARRIER barrier = {};
         barrier.Type                   = D3D12_RESOURCE_BARRIER_TYPE_TRANSITION;
@@ -189,13 +196,13 @@ int main(int, char**)
         barrier.Transition.Subresource = D3D12_RESOURCE_BARRIER_ALL_SUBRESOURCES;
         barrier.Transition.StateBefore = D3D12_RESOURCE_STATE_PRESENT;
         barrier.Transition.StateAfter  = D3D12_RESOURCE_STATE_RENDER_TARGET;
-        g_pd3dCommandList->Reset(frameCtx->CommandAllocator, NULL);
-        g_pd3dCommandList->ResourceBarrier(1, &barrier);
 
-        // Render Dear ImGui graphics
+        g_pd3dCommandList->Reset(frameCtxt->CommandAllocator, NULL);
+        g_pd3dCommandList->ResourceBarrier(1, &barrier);
         g_pd3dCommandList->ClearRenderTargetView(g_mainRenderTargetDescriptor[backBufferIdx], (float*)&clear_color, 0, NULL);
         g_pd3dCommandList->OMSetRenderTargets(1, &g_mainRenderTargetDescriptor[backBufferIdx], FALSE, NULL);
         g_pd3dCommandList->SetDescriptorHeaps(1, &g_pd3dSrvDescHeap);
+        ImGui::Render();
         ImGui_ImplDX12_RenderDrawData(ImGui::GetDrawData(), g_pd3dCommandList);
         barrier.Transition.StateBefore = D3D12_RESOURCE_STATE_RENDER_TARGET;
         barrier.Transition.StateAfter  = D3D12_RESOURCE_STATE_PRESENT;
@@ -204,18 +211,23 @@ int main(int, char**)
 
         g_pd3dCommandQueue->ExecuteCommandLists(1, (ID3D12CommandList* const*)&g_pd3dCommandList);
 
+        // Update and Render additional Platform Windows
+        if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+        {
+            ImGui::UpdatePlatformWindows();
+            ImGui::RenderPlatformWindowsDefault(NULL, (void*)g_pd3dCommandList);
+        }
+
         g_pSwapChain->Present(1, 0); // Present with vsync
         //g_pSwapChain->Present(0, 0); // Present without vsync
 
         UINT64 fenceValue = g_fenceLastSignaledValue + 1;
         g_pd3dCommandQueue->Signal(g_fence, fenceValue);
         g_fenceLastSignaledValue = fenceValue;
-        frameCtx->FenceValue = fenceValue;
+        frameCtxt->FenceValue = fenceValue;
     }
 
     WaitForLastSubmittedFrame();
-
-    // Cleanup
     ImGui_ImplDX12_Shutdown();
     ImGui_ImplWin32_Shutdown();
     ImGui::DestroyContext();
@@ -389,13 +401,13 @@ void CleanupRenderTarget()
 
 void WaitForLastSubmittedFrame()
 {
-    FrameContext* frameCtx = &g_frameContext[g_frameIndex % NUM_FRAMES_IN_FLIGHT];
+    FrameContext* frameCtxt = &g_frameContext[g_frameIndex % NUM_FRAMES_IN_FLIGHT];
 
-    UINT64 fenceValue = frameCtx->FenceValue;
+    UINT64 fenceValue = frameCtxt->FenceValue;
     if (fenceValue == 0)
         return; // No fence was signaled
 
-    frameCtx->FenceValue = 0;
+    frameCtxt->FenceValue = 0;
     if (g_fence->GetCompletedValue() >= fenceValue)
         return;
 
@@ -411,11 +423,11 @@ FrameContext* WaitForNextFrameResources()
     HANDLE waitableObjects[] = { g_hSwapChainWaitableObject, NULL };
     DWORD numWaitableObjects = 1;
 
-    FrameContext* frameCtx = &g_frameContext[nextFrameIndex % NUM_FRAMES_IN_FLIGHT];
-    UINT64 fenceValue = frameCtx->FenceValue;
+    FrameContext* frameCtxt = &g_frameContext[nextFrameIndex % NUM_FRAMES_IN_FLIGHT];
+    UINT64 fenceValue = frameCtxt->FenceValue;
     if (fenceValue != 0) // means no fence was signaled
     {
-        frameCtx->FenceValue = 0;
+        frameCtxt->FenceValue = 0;
         g_fence->SetEventOnCompletion(fenceValue, g_fenceEvent);
         waitableObjects[1] = g_fenceEvent;
         numWaitableObjects = 2;
@@ -423,7 +435,7 @@ FrameContext* WaitForNextFrameResources()
 
     WaitForMultipleObjects(numWaitableObjects, waitableObjects, TRUE, INFINITE);
 
-    return frameCtx;
+    return frameCtxt;
 }
 
 void ResizeSwapChain(HWND hWnd, int width, int height)

examples/example_win32_directx9/build_win32.bat

@@ -1,8 +1,3 @@
 @REM Build for Visual Studio compiler. Run your copy of vcvars32.bat or vcvarsall.bat to setup command-line compiler.
-@set OUT_DIR=Debug
-@set OUT_EXE=example_win32_directx9
-@set INCLUDES=/I..\.. /I..\..\backends /I "%DXSDK_DIR%/Include"
-@set SOURCES=main.cpp ..\..\backends\imgui_impl_dx9.cpp ..\..\backends\imgui_impl_win32.cpp ..\..\imgui*.cpp
-@set LIBS=/LIBPATH:"%DXSDK_DIR%/Lib/x86" d3d9.lib
-mkdir %OUT_DIR%
-cl /nologo /Zi /MD %INCLUDES% /D UNICODE /D _UNICODE %SOURCES% /Fe%OUT_DIR%/%OUT_EXE%.exe /Fo%OUT_DIR%/ /link %LIBS%
+mkdir Debug
+cl /nologo /Zi /MD /I .. /I ..\.. /I "%DXSDK_DIR%/Include" /D UNICODE /D _UNICODE *.cpp ..\..\backends\imgui_impl_dx9.cpp ..\..\backends\imgui_impl_win32.cpp ..\..\imgui*.cpp /FeDebug/example_win32_directx9.exe /FoDebug/ /link /LIBPATH:"%DXSDK_DIR%/Lib/x86" d3d9.lib

examples/example_win32_directx9/main.cpp

@@ -24,6 +24,8 @@ LRESULT WINAPI WndProc(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam);
 // Main code
 int main(int, char**)
 {
+    ImGui_ImplWin32_EnableDpiAwareness();
+
     // Create application window
     //ImGui_ImplWin32_EnableDpiAwareness();
     WNDCLASSEX wc = { sizeof(WNDCLASSEX), CS_CLASSDC, WndProc, 0L, 0L, GetModuleHandle(NULL), NULL, NULL, NULL, NULL, _T("ImGui Example"), NULL };
@@ -46,13 +48,25 @@ int main(int, char**)
     IMGUI_CHECKVERSION();
     ImGui::CreateContext();
     ImGuiIO& io = ImGui::GetIO(); (void)io;
-    //io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;     // Enable Keyboard Controls
+    io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;       // Enable Keyboard Controls
     //io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad;      // Enable Gamepad Controls
+    io.ConfigFlags |= ImGuiConfigFlags_DockingEnable;           // Enable Docking
+    io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable;         // Enable Multi-Viewport / Platform Windows
+    //io.ConfigViewportsNoAutoMerge = true;
+    //io.ConfigViewportsNoTaskBarIcon = true;
 
     // Setup Dear ImGui style
     ImGui::StyleColorsDark();
     //ImGui::StyleColorsClassic();
 
+    // When viewports are enabled we tweak WindowRounding/WindowBg so platform windows can look identical to regular ones.
+    ImGuiStyle& style = ImGui::GetStyle();
+    if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+    {
+        style.WindowRounding = 0.0f;
+        style.Colors[ImGuiCol_WindowBg].w = 1.0f;
+    }
+
     // Setup Platform/Renderer backends
     ImGui_ImplWin32_Init(hwnd);
     ImGui_ImplDX9_Init(g_pd3dDevice);
@@ -149,6 +163,14 @@ int main(int, char**)
             ImGui_ImplDX9_RenderDrawData(ImGui::GetDrawData());
             g_pd3dDevice->EndScene();
         }
+
+        // Update and Render additional Platform Windows
+        if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+        {
+            ImGui::UpdatePlatformWindows();
+            ImGui::RenderPlatformWindowsDefault();
+        }
+
         HRESULT result = g_pd3dDevice->Present(NULL, NULL, NULL, NULL);
 
         // Handle loss of D3D9 device
@@ -204,6 +226,10 @@ void ResetDevice()
     ImGui_ImplDX9_CreateDeviceObjects();
 }
 
+#ifndef WM_DPICHANGED
+#define WM_DPICHANGED 0x02E0 // From Windows SDK 8.1+ headers
+#endif
+
 // Forward declare message handler from imgui_impl_win32.cpp
 extern IMGUI_IMPL_API LRESULT ImGui_ImplWin32_WndProcHandler(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam);
 
@@ -230,6 +256,15 @@ LRESULT WINAPI WndProc(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam)
     case WM_DESTROY:
         ::PostQuitMessage(0);
         return 0;
+    case WM_DPICHANGED:
+        if (ImGui::GetIO().ConfigFlags & ImGuiConfigFlags_DpiEnableScaleViewports)
+        {
+            //const int dpi = HIWORD(wParam);
+            //printf("WM_DPICHANGED to %d (%.0f%%)\n", dpi, (float)dpi / 96.0f * 100.0f);
+            const RECT* suggested_rect = (RECT*)lParam;
+            ::SetWindowPos(hWnd, NULL, suggested_rect->left, suggested_rect->top, suggested_rect->right - suggested_rect->left, suggested_rect->bottom - suggested_rect->top, SWP_NOZORDER | SWP_NOACTIVATE);
+        }
+        break;
     }
     return ::DefWindowProc(hWnd, msg, wParam, lParam);
 }

examples/imgui_examples.sln

@@ -9,11 +9,21 @@ Project("{8BC9CEB8-8B4A-11D0-8D11-00A0C91BC942}") = "example_win32_directx10", "
 EndProject
 Project("{8BC9CEB8-8B4A-11D0-8D11-00A0C91BC942}") = "example_win32_directx11", "example_win32_directx11\example_win32_directx11.vcxproj", "{9F316E83-5AE5-4939-A723-305A94F48005}"
 EndProject
+Project("{8BC9CEB8-8B4A-11D0-8D11-00A0C91BC942}") = "example_win32_directx12", "example_win32_directx12\example_win32_directx12.vcxproj", "{B4CF9797-519D-4AFE-A8F4-5141A6B521D3}"
+EndProject
 Project("{8BC9CEB8-8B4A-11D0-8D11-00A0C91BC942}") = "example_glfw_opengl2", "example_glfw_opengl2\example_glfw_opengl2.vcxproj", "{9CDA7840-B7A5-496D-A527-E95571496D18}"
 EndProject
 Project("{8BC9CEB8-8B4A-11D0-8D11-00A0C91BC942}") = "example_glfw_opengl3", "example_glfw_opengl3\example_glfw_opengl3.vcxproj", "{4A1FB5EA-22F5-42A8-AB92-1D2DF5D47FB9}"
 EndProject
-Project("{8BC9CEB8-8B4A-11D0-8D11-00A0C91BC942}") = "example_win32_directx12", "example_win32_directx12\example_win32_directx12.vcxproj", "{B4CF9797-519D-4AFE-A8F4-5141A6B521D3}"
+Project("{8BC9CEB8-8B4A-11D0-8D11-00A0C91BC942}") = "example_glfw_vulkan", "example_glfw_vulkan\example_glfw_vulkan.vcxproj", "{57E2DF5A-6FC8-45BB-99DD-91A18C646E80}"
+EndProject
+Project("{8BC9CEB8-8B4A-11D0-8D11-00A0C91BC942}") = "example_sdl_opengl2", "example_sdl_opengl2\example_sdl_opengl2.vcxproj", "{2AE17FDE-F7F3-4CAC-ADAB-0710EDA4F741}"
+EndProject
+Project("{8BC9CEB8-8B4A-11D0-8D11-00A0C91BC942}") = "example_sdl_opengl3", "example_sdl_opengl3\example_sdl_opengl3.vcxproj", "{BBAEB705-1669-40F3-8567-04CF6A991F4C}"
+EndProject
+Project("{8BC9CEB8-8B4A-11D0-8D11-00A0C91BC942}") = "example_sdl_vulkan", "example_sdl_vulkan\example_sdl_vulkan.vcxproj", "{BAE3D0B5-9695-4EB1-AD0F-75890EB4A3B3}"
+EndProject
+Project("{8BC9CEB8-8B4A-11D0-8D11-00A0C91BC942}") = "example_sdl_directx11", "example_sdl_directx11\example_sdl_directx11.vcxproj", "{9E1987E3-1F19-45CA-B9C9-D31E791836D8}"
 EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
@@ -47,6 +57,14 @@ Global
 		{9F316E83-5AE5-4939-A723-305A94F48005}.Release|Win32.Build.0 = Release|Win32
 		{9F316E83-5AE5-4939-A723-305A94F48005}.Release|x64.ActiveCfg = Release|x64
 		{9F316E83-5AE5-4939-A723-305A94F48005}.Release|x64.Build.0 = Release|x64
+		{B4CF9797-519D-4AFE-A8F4-5141A6B521D3}.Debug|Win32.ActiveCfg = Debug|Win32
+		{B4CF9797-519D-4AFE-A8F4-5141A6B521D3}.Debug|Win32.Build.0 = Debug|Win32
+		{B4CF9797-519D-4AFE-A8F4-5141A6B521D3}.Debug|x64.ActiveCfg = Debug|x64
+		{B4CF9797-519D-4AFE-A8F4-5141A6B521D3}.Debug|x64.Build.0 = Debug|x64
+		{B4CF9797-519D-4AFE-A8F4-5141A6B521D3}.Release|Win32.ActiveCfg = Release|Win32
+		{B4CF9797-519D-4AFE-A8F4-5141A6B521D3}.Release|Win32.Build.0 = Release|Win32
+		{B4CF9797-519D-4AFE-A8F4-5141A6B521D3}.Release|x64.ActiveCfg = Release|x64
+		{B4CF9797-519D-4AFE-A8F4-5141A6B521D3}.Release|x64.Build.0 = Release|x64
 		{9CDA7840-B7A5-496D-A527-E95571496D18}.Debug|Win32.ActiveCfg = Debug|Win32
 		{9CDA7840-B7A5-496D-A527-E95571496D18}.Debug|Win32.Build.0 = Debug|Win32
 		{9CDA7840-B7A5-496D-A527-E95571496D18}.Debug|x64.ActiveCfg = Debug|x64
@@ -63,14 +81,46 @@ Global
 		{4A1FB5EA-22F5-42A8-AB92-1D2DF5D47FB9}.Release|Win32.Build.0 = Release|Win32
 		{4A1FB5EA-22F5-42A8-AB92-1D2DF5D47FB9}.Release|x64.ActiveCfg = Release|x64
 		{4A1FB5EA-22F5-42A8-AB92-1D2DF5D47FB9}.Release|x64.Build.0 = Release|x64
-		{B4CF9797-519D-4AFE-A8F4-5141A6B521D3}.Debug|Win32.ActiveCfg = Debug|Win32
-		{B4CF9797-519D-4AFE-A8F4-5141A6B521D3}.Debug|Win32.Build.0 = Debug|Win32
-		{B4CF9797-519D-4AFE-A8F4-5141A6B521D3}.Debug|x64.ActiveCfg = Debug|x64
-		{B4CF9797-519D-4AFE-A8F4-5141A6B521D3}.Debug|x64.Build.0 = Debug|x64
-		{B4CF9797-519D-4AFE-A8F4-5141A6B521D3}.Release|Win32.ActiveCfg = Release|Win32
-		{B4CF9797-519D-4AFE-A8F4-5141A6B521D3}.Release|Win32.Build.0 = Release|Win32
-		{B4CF9797-519D-4AFE-A8F4-5141A6B521D3}.Release|x64.ActiveCfg = Release|x64
-		{B4CF9797-519D-4AFE-A8F4-5141A6B521D3}.Release|x64.Build.0 = Release|x64
+		{57E2DF5A-6FC8-45BB-99DD-91A18C646E80}.Debug|Win32.ActiveCfg = Debug|Win32
+		{57E2DF5A-6FC8-45BB-99DD-91A18C646E80}.Debug|Win32.Build.0 = Debug|Win32
+		{57E2DF5A-6FC8-45BB-99DD-91A18C646E80}.Debug|x64.ActiveCfg = Debug|x64
+		{57E2DF5A-6FC8-45BB-99DD-91A18C646E80}.Debug|x64.Build.0 = Debug|x64
+		{57E2DF5A-6FC8-45BB-99DD-91A18C646E80}.Release|Win32.ActiveCfg = Release|Win32
+		{57E2DF5A-6FC8-45BB-99DD-91A18C646E80}.Release|Win32.Build.0 = Release|Win32
+		{57E2DF5A-6FC8-45BB-99DD-91A18C646E80}.Release|x64.ActiveCfg = Release|x64
+		{57E2DF5A-6FC8-45BB-99DD-91A18C646E80}.Release|x64.Build.0 = Release|x64
+		{2AE17FDE-F7F3-4CAC-ADAB-0710EDA4F741}.Debug|Win32.ActiveCfg = Debug|Win32
+		{2AE17FDE-F7F3-4CAC-ADAB-0710EDA4F741}.Debug|Win32.Build.0 = Debug|Win32
+		{2AE17FDE-F7F3-4CAC-ADAB-0710EDA4F741}.Debug|x64.ActiveCfg = Debug|x64
+		{2AE17FDE-F7F3-4CAC-ADAB-0710EDA4F741}.Debug|x64.Build.0 = Debug|x64
+		{2AE17FDE-F7F3-4CAC-ADAB-0710EDA4F741}.Release|Win32.ActiveCfg = Release|Win32
+		{2AE17FDE-F7F3-4CAC-ADAB-0710EDA4F741}.Release|Win32.Build.0 = Release|Win32
+		{2AE17FDE-F7F3-4CAC-ADAB-0710EDA4F741}.Release|x64.ActiveCfg = Release|x64
+		{2AE17FDE-F7F3-4CAC-ADAB-0710EDA4F741}.Release|x64.Build.0 = Release|x64
+		{BBAEB705-1669-40F3-8567-04CF6A991F4C}.Debug|Win32.ActiveCfg = Debug|Win32
+		{BBAEB705-1669-40F3-8567-04CF6A991F4C}.Debug|Win32.Build.0 = Debug|Win32
+		{BBAEB705-1669-40F3-8567-04CF6A991F4C}.Debug|x64.ActiveCfg = Debug|x64
+		{BBAEB705-1669-40F3-8567-04CF6A991F4C}.Debug|x64.Build.0 = Debug|x64
+		{BBAEB705-1669-40F3-8567-04CF6A991F4C}.Release|Win32.ActiveCfg = Release|Win32
+		{BBAEB705-1669-40F3-8567-04CF6A991F4C}.Release|Win32.Build.0 = Release|Win32
+		{BBAEB705-1669-40F3-8567-04CF6A991F4C}.Release|x64.ActiveCfg = Release|x64
+		{BBAEB705-1669-40F3-8567-04CF6A991F4C}.Release|x64.Build.0 = Release|x64
+		{BAE3D0B5-9695-4EB1-AD0F-75890EB4A3B3}.Debug|Win32.ActiveCfg = Debug|Win32
+		{BAE3D0B5-9695-4EB1-AD0F-75890EB4A3B3}.Debug|Win32.Build.0 = Debug|Win32
+		{BAE3D0B5-9695-4EB1-AD0F-75890EB4A3B3}.Debug|x64.ActiveCfg = Debug|x64
+		{BAE3D0B5-9695-4EB1-AD0F-75890EB4A3B3}.Debug|x64.Build.0 = Debug|x64
+		{BAE3D0B5-9695-4EB1-AD0F-75890EB4A3B3}.Release|Win32.ActiveCfg = Release|Win32
+		{BAE3D0B5-9695-4EB1-AD0F-75890EB4A3B3}.Release|Win32.Build.0 = Release|Win32
+		{BAE3D0B5-9695-4EB1-AD0F-75890EB4A3B3}.Release|x64.ActiveCfg = Release|x64
+		{BAE3D0B5-9695-4EB1-AD0F-75890EB4A3B3}.Release|x64.Build.0 = Release|x64
+		{9E1987E3-1F19-45CA-B9C9-D31E791836D8}.Debug|Win32.ActiveCfg = Debug|Win32
+		{9E1987E3-1F19-45CA-B9C9-D31E791836D8}.Debug|Win32.Build.0 = Debug|Win32
+		{9E1987E3-1F19-45CA-B9C9-D31E791836D8}.Debug|x64.ActiveCfg = Debug|x64
+		{9E1987E3-1F19-45CA-B9C9-D31E791836D8}.Debug|x64.Build.0 = Debug|x64
+		{9E1987E3-1F19-45CA-B9C9-D31E791836D8}.Release|Win32.ActiveCfg = Release|Win32
+		{9E1987E3-1F19-45CA-B9C9-D31E791836D8}.Release|Win32.Build.0 = Release|Win32
+		{9E1987E3-1F19-45CA-B9C9-D31E791836D8}.Release|x64.ActiveCfg = Release|x64
+		{9E1987E3-1F19-45CA-B9C9-D31E791836D8}.Release|x64.Build.0 = Release|x64
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE

imconfig.h

@@ -59,8 +59,8 @@
 //#define IMGUI_DISABLE_STB_TRUETYPE_IMPLEMENTATION
 //#define IMGUI_DISABLE_STB_RECT_PACK_IMPLEMENTATION
 
-//---- Use stb_printf's faster implementation of vsnprintf instead of the one from libc (unless IMGUI_DISABLE_DEFAULT_FORMAT_FUNCTIONS is defined)
-// Requires 'stb_sprintf.h' to be available in the include path. Compatibility checks of arguments and formats done by clang and GCC will be disabled in order to support the extra formats provided by STB sprintf.
+//---- Unless IMGUI_DISABLE_DEFAULT_FORMAT_FUNCTIONS is defined, use the much faster STB sprintf library implementation of vsnprintf instead of the one from the default C library.
+// Note that stb_sprintf.h is meant to be provided by the user and available in the include path at compile time. Also, the compatibility checks of the arguments and formats done by clang and GCC will be disabled in order to support the extra formats provided by STB sprintf.
 // #define IMGUI_USE_STB_SPRINTF
 
 //---- Define constructor and implicit cast operators to convert back<>forth between your math types and ImVec2/ImVec4.

imgui_draw.cpp

@@ -1,4 +1,4 @@
-// dear imgui, v1.80
+// dear imgui, v1.80 WIP
 // (drawing and font code)
 
 /*
@@ -210,7 +210,7 @@ void ImGui::StyleColorsDark(ImGuiStyle* dst)
     colors[ImGuiCol_Separator]              = colors[ImGuiCol_Border];
     colors[ImGuiCol_SeparatorHovered]       = ImVec4(0.10f, 0.40f, 0.75f, 0.78f);
     colors[ImGuiCol_SeparatorActive]        = ImVec4(0.10f, 0.40f, 0.75f, 1.00f);
-    colors[ImGuiCol_ResizeGrip]             = ImVec4(0.26f, 0.59f, 0.98f, 0.20f);
+    colors[ImGuiCol_ResizeGrip]             = ImVec4(0.26f, 0.59f, 0.98f, 0.25f);
     colors[ImGuiCol_ResizeGripHovered]      = ImVec4(0.26f, 0.59f, 0.98f, 0.67f);
     colors[ImGuiCol_ResizeGripActive]       = ImVec4(0.26f, 0.59f, 0.98f, 0.95f);
     colors[ImGuiCol_Tab]                    = ImLerp(colors[ImGuiCol_Header],       colors[ImGuiCol_TitleBgActive], 0.80f);
@@ -218,6 +218,8 @@ void ImGui::StyleColorsDark(ImGuiStyle* dst)
     colors[ImGuiCol_TabActive]              = ImLerp(colors[ImGuiCol_HeaderActive], colors[ImGuiCol_TitleBgActive], 0.60f);
     colors[ImGuiCol_TabUnfocused]           = ImLerp(colors[ImGuiCol_Tab],          colors[ImGuiCol_TitleBg], 0.80f);
     colors[ImGuiCol_TabUnfocusedActive]     = ImLerp(colors[ImGuiCol_TabActive],    colors[ImGuiCol_TitleBg], 0.40f);
+    colors[ImGuiCol_DockingPreview]         = colors[ImGuiCol_HeaderActive] * ImVec4(1.0f, 1.0f, 1.0f, 0.7f);
+    colors[ImGuiCol_DockingEmptyBg]         = ImVec4(0.20f, 0.20f, 0.20f, 1.00f);
     colors[ImGuiCol_PlotLines]              = ImVec4(0.61f, 0.61f, 0.61f, 1.00f);
     colors[ImGuiCol_PlotLinesHovered]       = ImVec4(1.00f, 0.43f, 0.35f, 1.00f);
     colors[ImGuiCol_PlotHistogram]          = ImVec4(0.90f, 0.70f, 0.00f, 1.00f);
@@ -242,7 +244,7 @@ void ImGui::StyleColorsClassic(ImGuiStyle* dst)
 
     colors[ImGuiCol_Text]                   = ImVec4(0.90f, 0.90f, 0.90f, 1.00f);
     colors[ImGuiCol_TextDisabled]           = ImVec4(0.60f, 0.60f, 0.60f, 1.00f);
-    colors[ImGuiCol_WindowBg]               = ImVec4(0.00f, 0.00f, 0.00f, 0.85f);
+    colors[ImGuiCol_WindowBg]               = ImVec4(0.00f, 0.00f, 0.00f, 0.70f);
     colors[ImGuiCol_ChildBg]                = ImVec4(0.00f, 0.00f, 0.00f, 0.00f);
     colors[ImGuiCol_PopupBg]                = ImVec4(0.11f, 0.11f, 0.14f, 0.92f);
     colors[ImGuiCol_Border]                 = ImVec4(0.50f, 0.50f, 0.50f, 0.50f);
@@ -270,7 +272,7 @@ void ImGui::StyleColorsClassic(ImGuiStyle* dst)
     colors[ImGuiCol_Separator]              = ImVec4(0.50f, 0.50f, 0.50f, 0.60f);
     colors[ImGuiCol_SeparatorHovered]       = ImVec4(0.60f, 0.60f, 0.70f, 1.00f);
     colors[ImGuiCol_SeparatorActive]        = ImVec4(0.70f, 0.70f, 0.90f, 1.00f);
-    colors[ImGuiCol_ResizeGrip]             = ImVec4(1.00f, 1.00f, 1.00f, 0.10f);
+    colors[ImGuiCol_ResizeGrip]             = ImVec4(1.00f, 1.00f, 1.00f, 0.16f);
     colors[ImGuiCol_ResizeGripHovered]      = ImVec4(0.78f, 0.82f, 1.00f, 0.60f);
     colors[ImGuiCol_ResizeGripActive]       = ImVec4(0.78f, 0.82f, 1.00f, 0.90f);
     colors[ImGuiCol_Tab]                    = ImLerp(colors[ImGuiCol_Header],       colors[ImGuiCol_TitleBgActive], 0.80f);
@@ -278,6 +280,8 @@ void ImGui::StyleColorsClassic(ImGuiStyle* dst)
     colors[ImGuiCol_TabActive]              = ImLerp(colors[ImGuiCol_HeaderActive], colors[ImGuiCol_TitleBgActive], 0.60f);
     colors[ImGuiCol_TabUnfocused]           = ImLerp(colors[ImGuiCol_Tab],          colors[ImGuiCol_TitleBg], 0.80f);
     colors[ImGuiCol_TabUnfocusedActive]     = ImLerp(colors[ImGuiCol_TabActive],    colors[ImGuiCol_TitleBg], 0.40f);
+    colors[ImGuiCol_DockingPreview]         = colors[ImGuiCol_Header] * ImVec4(1.0f, 1.0f, 1.0f, 0.7f);
+    colors[ImGuiCol_DockingEmptyBg]         = ImVec4(0.20f, 0.20f, 0.20f, 1.00f);
     colors[ImGuiCol_PlotLines]              = ImVec4(1.00f, 1.00f, 1.00f, 1.00f);
     colors[ImGuiCol_PlotLinesHovered]       = ImVec4(0.90f, 0.70f, 0.00f, 1.00f);
     colors[ImGuiCol_PlotHistogram]          = ImVec4(0.90f, 0.70f, 0.00f, 1.00f);
@@ -331,7 +335,7 @@ void ImGui::StyleColorsLight(ImGuiStyle* dst)
     colors[ImGuiCol_Separator]              = ImVec4(0.39f, 0.39f, 0.39f, 0.62f);
     colors[ImGuiCol_SeparatorHovered]       = ImVec4(0.14f, 0.44f, 0.80f, 0.78f);
     colors[ImGuiCol_SeparatorActive]        = ImVec4(0.14f, 0.44f, 0.80f, 1.00f);
-    colors[ImGuiCol_ResizeGrip]             = ImVec4(0.35f, 0.35f, 0.35f, 0.17f);
+    colors[ImGuiCol_ResizeGrip]             = ImVec4(0.80f, 0.80f, 0.80f, 0.56f);
     colors[ImGuiCol_ResizeGripHovered]      = ImVec4(0.26f, 0.59f, 0.98f, 0.67f);
     colors[ImGuiCol_ResizeGripActive]       = ImVec4(0.26f, 0.59f, 0.98f, 0.95f);
     colors[ImGuiCol_Tab]                    = ImLerp(colors[ImGuiCol_Header],       colors[ImGuiCol_TitleBgActive], 0.90f);
@@ -339,6 +343,8 @@ void ImGui::StyleColorsLight(ImGuiStyle* dst)
     colors[ImGuiCol_TabActive]              = ImLerp(colors[ImGuiCol_HeaderActive], colors[ImGuiCol_TitleBgActive], 0.60f);
     colors[ImGuiCol_TabUnfocused]           = ImLerp(colors[ImGuiCol_Tab],          colors[ImGuiCol_TitleBg], 0.80f);
     colors[ImGuiCol_TabUnfocusedActive]     = ImLerp(colors[ImGuiCol_TabActive],    colors[ImGuiCol_TitleBg], 0.40f);
+    colors[ImGuiCol_DockingPreview]         = colors[ImGuiCol_Header] * ImVec4(1.0f, 1.0f, 1.0f, 0.7f);
+    colors[ImGuiCol_DockingEmptyBg]         = ImVec4(0.20f, 0.20f, 0.20f, 1.00f);
     colors[ImGuiCol_PlotLines]              = ImVec4(0.39f, 0.39f, 0.39f, 1.00f);
     colors[ImGuiCol_PlotLinesHovered]       = ImVec4(1.00f, 0.43f, 0.35f, 1.00f);
     colors[ImGuiCol_PlotHistogram]          = ImVec4(0.90f, 0.70f, 0.00f, 1.00f);
@@ -405,7 +411,6 @@ void ImDrawList::_ResetForNewFrame()
     _Path.resize(0);
     _Splitter.Clear();
     CmdBuffer.push_back(ImDrawCmd());
-    _FringeScale = 1.0f;
 }
 
 void ImDrawList::_ClearFreeMemory()
@@ -681,12 +686,12 @@ void ImDrawList::AddPolyline(const ImVec2* points, const int points_count, ImU32
 
     const ImVec2 opaque_uv = _Data->TexUvWhitePixel;
     const int count = closed ? points_count : points_count - 1; // The number of line segments we need to draw
-    const bool thick_line = (thickness > _FringeScale);
+    const bool thick_line = (thickness > 1.0f);
 
     if (Flags & ImDrawListFlags_AntiAliasedLines)
     {
         // Anti-aliased stroke
-        const float AA_SIZE = _FringeScale;
+        const float AA_SIZE = 1.0f;
         const ImU32 col_trans = col & ~IM_COL32_A_MASK;
 
         // Thicknesses <1.0 should behave like thickness 1.0
@@ -697,7 +702,7 @@ void ImDrawList::AddPolyline(const ImVec2* points, const int points_count, ImU32
         // Do we want to draw this line using a texture?
         // - For now, only draw integer-width lines using textures to avoid issues with the way scaling occurs, could be improved.
         // - If AA_SIZE is not 1.0f we cannot use the texture path.
-        const bool use_texture = (Flags & ImDrawListFlags_AntiAliasedLinesUseTex) && (integer_thickness < IM_DRAWLIST_TEX_LINES_WIDTH_MAX) && (fractional_thickness <= 0.00001f) && (AA_SIZE == 1.0f);
+        const bool use_texture = (Flags & ImDrawListFlags_AntiAliasedLinesUseTex) && (integer_thickness < IM_DRAWLIST_TEX_LINES_WIDTH_MAX) && (fractional_thickness <= 0.00001f);
 
         // We should never hit this, because NewFrame() doesn't set ImDrawListFlags_AntiAliasedLinesUseTex unless ImFontAtlasFlags_NoBakedLines is off
         IM_ASSERT_PARANOID(!use_texture || !(_Data->Font->ContainerAtlas->Flags & ImFontAtlasFlags_NoBakedLines));
@@ -939,7 +944,7 @@ void ImDrawList::AddConvexPolyFilled(const ImVec2* points, const int points_coun
     if (Flags & ImDrawListFlags_AntiAliasedFill)
     {
         // Anti-aliased Fill
-        const float AA_SIZE = _FringeScale;
+        const float AA_SIZE = 1.0f;
         const ImU32 col_trans = col & ~IM_COL32_A_MASK;
         const int idx_count = (points_count - 2)*3 + points_count * 6;
         const int vtx_count = (points_count * 2);
@@ -1051,7 +1056,7 @@ void ImDrawList::PathArcTo(const ImVec2& center, float radius, float a_min, floa
     }
 }
 
-ImVec2 ImBezierCubicCalc(const ImVec2& p1, const ImVec2& p2, const ImVec2& p3, const ImVec2& p4, float t)
+ImVec2 ImBezierCalc(const ImVec2& p1, const ImVec2& p2, const ImVec2& p3, const ImVec2& p4, float t)
 {
     float u = 1.0f - t;
     float w1 = u*u*u;
@@ -1061,22 +1066,13 @@ ImVec2 ImBezierCubicCalc(const ImVec2& p1, const ImVec2& p2, const ImVec2& p3, c
     return ImVec2(w1*p1.x + w2*p2.x + w3*p3.x + w4*p4.x, w1*p1.y + w2*p2.y + w3*p3.y + w4*p4.y);
 }
 
-ImVec2 ImBezierQuadraticCalc(const ImVec2& p1, const ImVec2& p2, const ImVec2& p3, float t)
-{
-    float u = 1.0f - t;
-    float w1 = u * u;
-    float w2 = 2 * u * t;
-    float w3 = t * t;
-    return ImVec2(w1 * p1.x + w2 * p2.x + w3 * p3.x, w1 * p1.y + w2 * p2.y + w3 * p3.y);
-}
-
-// Closely mimics ImBezierCubicClosestPointCasteljau() in imgui.cpp
-static void PathBezierCubicCurveToCasteljau(ImVector<ImVec2>* path, float x1, float y1, float x2, float y2, float x3, float y3, float x4, float y4, float tess_tol, int level)
+// Closely mimics BezierClosestPointCasteljauStep() in imgui.cpp
+static void PathBezierToCasteljau(ImVector<ImVec2>* path, float x1, float y1, float x2, float y2, float x3, float y3, float x4, float y4, float tess_tol, int level)
 {
     float dx = x4 - x1;
     float dy = y4 - y1;
-    float d2 = (x2 - x4) * dy - (y2 - y4) * dx;
-    float d3 = (x3 - x4) * dy - (y3 - y4) * dx;
+    float d2 = ((x2 - x4) * dy - (y2 - y4) * dx);
+    float d3 = ((x3 - x4) * dy - (y3 - y4) * dx);
     d2 = (d2 >= 0) ? d2 : -d2;
     d3 = (d3 >= 0) ? d3 : -d3;
     if ((d2 + d3) * (d2 + d3) < tess_tol * (dx * dx + dy * dy))
@@ -1091,56 +1087,23 @@ static void PathBezierCubicCurveToCasteljau(ImVector<ImVec2>* path, float x1, fl
         float x123 = (x12 + x23)*0.5f,    y123 = (y12 + y23)*0.5f;
         float x234 = (x23 + x34)*0.5f,    y234 = (y23 + y34)*0.5f;
         float x1234 = (x123 + x234)*0.5f, y1234 = (y123 + y234)*0.5f;
-        PathBezierCubicCurveToCasteljau(path, x1, y1, x12, y12, x123, y123, x1234, y1234, tess_tol, level + 1);
-        PathBezierCubicCurveToCasteljau(path, x1234, y1234, x234, y234, x34, y34, x4, y4, tess_tol, level + 1);
+        PathBezierToCasteljau(path, x1, y1,        x12, y12,    x123, y123,  x1234, y1234, tess_tol, level + 1);
+        PathBezierToCasteljau(path, x1234, y1234,  x234, y234,  x34, y34,    x4, y4,       tess_tol, level + 1);
     }
 }
 
-static void PathBezierQuadraticCurveToCasteljau(ImVector<ImVec2>* path, float x1, float y1, float x2, float y2, float x3, float y3, float tess_tol, int level)
-{
-    float dx = x3 - x1, dy = y3 - y1;
-    float det = (x2 - x3) * dy - (y2 - y3) * dx;
-    if (det * det * 4.0f < tess_tol * (dx * dx + dy * dy))
-    {
-        path->push_back(ImVec2(x3, y3));
-    }
-    else if (level < 10)
-    {
-        float x12 = (x1 + x2) * 0.5f, y12 = (y1 + y2) * 0.5f;
-        float x23 = (x2 + x3) * 0.5f, y23 = (y2 + y3) * 0.5f;
-        float x123 = (x12 + x23) * 0.5f, y123 = (y12 + y23) * 0.5f;
-        PathBezierQuadraticCurveToCasteljau(path, x1, y1, x12, y12, x123, y123, tess_tol, level + 1);
-        PathBezierQuadraticCurveToCasteljau(path, x123, y123, x23, y23, x3, y3, tess_tol, level + 1);
-    }
-}
-
-void ImDrawList::PathBezierCubicCurveTo(const ImVec2& p2, const ImVec2& p3, const ImVec2& p4, int num_segments)
+void ImDrawList::PathBezierCurveTo(const ImVec2& p2, const ImVec2& p3, const ImVec2& p4, int num_segments)
 {
     ImVec2 p1 = _Path.back();
     if (num_segments == 0)
     {
-        PathBezierCubicCurveToCasteljau(&_Path, p1.x, p1.y, p2.x, p2.y, p3.x, p3.y, p4.x, p4.y, _Data->CurveTessellationTol, 0); // Auto-tessellated
+        PathBezierToCasteljau(&_Path, p1.x, p1.y, p2.x, p2.y, p3.x, p3.y, p4.x, p4.y, _Data->CurveTessellationTol, 0); // Auto-tessellated
     }
     else
     {
         float t_step = 1.0f / (float)num_segments;
         for (int i_step = 1; i_step <= num_segments; i_step++)
-            _Path.push_back(ImBezierCubicCalc(p1, p2, p3, p4, t_step * i_step));
-    }
-}
-
-void ImDrawList::PathBezierQuadraticCurveTo(const ImVec2& p2, const ImVec2& p3, int num_segments)
-{
-    ImVec2 p1 = _Path.back();
-    if (num_segments == 0)
-    {
-        PathBezierQuadraticCurveToCasteljau(&_Path, p1.x, p1.y, p2.x, p2.y, p3.x, p3.y, _Data->CurveTessellationTol, 0);// Auto-tessellated
-    }
-    else
-    {
-        float t_step = 1.0f / (float)num_segments;
-        for (int i_step = 1; i_step <= num_segments; i_step++)
-            _Path.push_back(ImBezierQuadraticCalc(p1, p2, p3, t_step * i_step));
+            _Path.push_back(ImBezierCalc(p1, p2, p3, p4, t_step * i_step));
     }
 }
 
@@ -1354,24 +1317,13 @@ void ImDrawList::AddNgonFilled(const ImVec2& center, float radius, ImU32 col, in
 }
 
 // Cubic Bezier takes 4 controls points
-void ImDrawList::AddBezierCubic(const ImVec2& p1, const ImVec2& p2, const ImVec2& p3, const ImVec2& p4, ImU32 col, float thickness, int num_segments)
+void ImDrawList::AddBezierCurve(const ImVec2& p1, const ImVec2& p2, const ImVec2& p3, const ImVec2& p4, ImU32 col, float thickness, int num_segments)
 {
     if ((col & IM_COL32_A_MASK) == 0)
         return;
 
     PathLineTo(p1);
-    PathBezierCubicCurveTo(p2, p3, p4, num_segments);
-    PathStroke(col, false, thickness);
-}
-
-// Quadratic Bezier takes 3 controls points
-void ImDrawList::AddBezierQuadratic(const ImVec2& p1, const ImVec2& p2, const ImVec2& p3, ImU32 col, float thickness, int num_segments)
-{
-    if ((col & IM_COL32_A_MASK) == 0)
-        return;
-
-    PathLineTo(p1);
-    PathBezierQuadraticCurveTo(p2, p3, num_segments);
+    PathBezierCurveTo(p2, p3, p4, num_segments);
     PathStroke(col, false, thickness);
 }
 
@@ -2171,11 +2123,10 @@ bool    ImFontAtlasBuildWithStbTruetype(ImFontAtlas* atlas)
         for (int output_i = 0; output_i < atlas->Fonts.Size && src_tmp.DstIndex == -1; output_i++)
             if (cfg.DstFont == atlas->Fonts[output_i])
                 src_tmp.DstIndex = output_i;
-        if (src_tmp.DstIndex == -1)
-        {
         IM_ASSERT(src_tmp.DstIndex != -1); // cfg.DstFont not pointing within atlas->Fonts[] array?
+        if (src_tmp.DstIndex == -1)
             return false;
-        }
+
         // Initialize helper structure for font loading and verify that the TTF/OTF data is correct
         const int font_offset = stbtt_GetFontOffsetForIndex((unsigned char*)cfg.FontData, cfg.FontNo);
         IM_ASSERT(font_offset >= 0 && "FontData is incorrect, or FontNo cannot be found.");
@@ -3457,8 +3408,10 @@ void ImFont::RenderText(ImDrawList* draw_list, float size, ImVec2 pos, ImU32 col
 // - RenderBullet()
 // - RenderCheckMark()
 // - RenderMouseCursor()
+// - RenderArrowDockMenu()
 // - RenderArrowPointingAt()
 // - RenderRectFilledRangeH()
+// - RenderRectFilledWithHole()
 //-----------------------------------------------------------------------------
 // Function in need of a redesign (legacy mess)
 // - RenderColorRectWithAlphaCheckerboard()
@@ -3550,6 +3503,14 @@ void ImGui::RenderArrowPointingAt(ImDrawList* draw_list, ImVec2 pos, ImVec2 half
     }
 }
 
+// This is less wide than RenderArrow() and we use in dock nodes instead of the regular RenderArrow() to denote a change of functionality,
+// and because the saved space means that the left-most tab label can stay at exactly the same position as the label of a loose window.
+void ImGui::RenderArrowDockMenu(ImDrawList* draw_list, ImVec2 p_min, float sz, ImU32 col)
+{
+    draw_list->AddRectFilled(p_min + ImVec2(sz * 0.10f, sz * 0.15f), p_min + ImVec2(sz * 0.70f, sz * 0.30f), col);
+    RenderArrowPointingAt(draw_list, p_min + ImVec2(sz * 0.40f, sz * 0.85f), ImVec2(sz * 0.30f, sz * 0.40f), ImGuiDir_Down, col);
+}
+
 static inline float ImAcos01(float x)
 {
     if (x <= 0.0f) return IM_PI * 0.5f;

imgui_internal.h

@@ -1,4 +1,4 @@
-// dear imgui, v1.80
+// dear imgui, v1.80 WIP
 // (internal structures/api)
 
 // You may use this file to debug, understand or extend ImGui features but we don't provide any guarantee of forward compatibility!
@@ -95,6 +95,10 @@ struct ImGuiColorMod;               // Stacked color modifier, backup of modifie
 struct ImGuiContext;                // Main Dear ImGui context
 struct ImGuiContextHook;            // Hook for extensions like ImGuiTestEngine
 struct ImGuiDataTypeInfo;           // Type information associated to a ImGuiDataType enum
+struct ImGuiDockContext;            // Docking system context
+struct ImGuiDockRequest;            // Docking system dock/undock queued request
+struct ImGuiDockNode;               // Docking system node (hold a list of Windows OR two child dock nodes)
+struct ImGuiDockNodeSettings;       // Storage for a dock node in .ini file (we preserve those even if the associated dock node isn't active during the session)
 struct ImGuiGroupData;              // Stacked storage data for BeginGroup()/EndGroup()
 struct ImGuiInputTextState;         // Internal state of the currently focused/edited text input box
 struct ImGuiLastItemDataBackup;     // Backup and restore IsItemHovered() internal data
@@ -120,6 +124,7 @@ struct ImGuiWindowTempData;         // Temporary storage for one window (that's
 struct ImGuiWindowSettings;         // Storage for a window .ini settings (we keep one of those even if the actual window wasn't instanced during this session)
 
 // Use your programming IDE "Go to definition" facility on the names of the center columns to find the actual flags/enum lists.
+typedef int ImGuiDataAuthority;         // -> enum ImGuiDataAuthority_      // Enum: for storing the source authority (dock node vs window) of a field
 typedef int ImGuiLayoutType;            // -> enum ImGuiLayoutType_         // Enum: Horizontal or vertical
 typedef int ImGuiItemFlags;             // -> enum ImGuiItemFlags_          // Flags: for PushItemFlag()
 typedef int ImGuiItemStatusFlags;       // -> enum ImGuiItemStatusFlags_    // Flags: for DC.LastItemStatusFlags
@@ -166,6 +171,9 @@ namespace ImStb
 // [SECTION] Macros
 //-----------------------------------------------------------------------------
 
+// Internal Drag and Drop payload types. String starting with '_' are reserved for Dear ImGui.
+#define IMGUI_PAYLOAD_TYPE_WINDOW       "_IMWINDOW"     // Payload == ImGuiWindow*
+
 // Debug Logging
 #ifndef IMGUI_DEBUG_LOG
 #define IMGUI_DEBUG_LOG(_FMT,...)       printf("[%05d] " _FMT, GImGui->FrameCount, __VA_ARGS__)
@@ -173,12 +181,16 @@ namespace ImStb
 
 // Debug Logging for selected systems. Remove the '((void)0) //' to enable.
 //#define IMGUI_DEBUG_LOG_POPUP         IMGUI_DEBUG_LOG // Enable log
+//#define IMGUI_DEBUG_LOG_VIEWPORT      IMGUI_DEBUG_LOG // Enable log
+//#define IMGUI_DEBUG_LOG_DOCKING       IMGUI_DEBUG_LOG // Enable log
 //#define IMGUI_DEBUG_LOG_NAV           IMGUI_DEBUG_LOG // Enable log
 #define IMGUI_DEBUG_LOG_POPUP(...)      ((void)0)       // Disable log
 #define IMGUI_DEBUG_LOG_NAV(...)        ((void)0)       // Disable log
+#define IMGUI_DEBUG_LOG_VIEWPORT(...)   ((void)0)       // Disable log
+#define IMGUI_DEBUG_LOG_DOCKING(...)    ((void)0)       // Disable log
 
 // Static Asserts
-#if (__cplusplus >= 201100) || (defined(_MSVC_LANG) && _MSVC_LANG >= 201100)
+#if (__cplusplus >= 201100)
 #define IM_STATIC_ASSERT(_COND)         static_assert(_COND, "")
 #else
 #define IM_STATIC_ASSERT(_COND)         typedef char static_assertion_##__line__[(_COND)?1:-1]
@@ -396,10 +408,9 @@ static inline float  ImLinearSweep(float current, float target, float speed)
 static inline ImVec2 ImMul(const ImVec2& lhs, const ImVec2& rhs)                { return ImVec2(lhs.x * rhs.x, lhs.y * rhs.y); }
 
 // Helpers: Geometry
-IMGUI_API ImVec2     ImBezierCubicCalc(const ImVec2& p1, const ImVec2& p2, const ImVec2& p3, const ImVec2& p4, float t);
-IMGUI_API ImVec2     ImBezierCubicClosestPoint(const ImVec2& p1, const ImVec2& p2, const ImVec2& p3, const ImVec2& p4, const ImVec2& p, int num_segments);       // For curves with explicit number of segments
-IMGUI_API ImVec2     ImBezierCubicClosestPointCasteljau(const ImVec2& p1, const ImVec2& p2, const ImVec2& p3, const ImVec2& p4, const ImVec2& p, float tess_tol);// For auto-tessellated curves you can use tess_tol = style.CurveTessellationTol
-IMGUI_API ImVec2     ImBezierQuadraticCalc(const ImVec2& p1, const ImVec2& p2, const ImVec2& p3, float t);
+IMGUI_API ImVec2     ImBezierCalc(const ImVec2& p1, const ImVec2& p2, const ImVec2& p3, const ImVec2& p4, float t);                                         // Cubic Bezier
+IMGUI_API ImVec2     ImBezierClosestPoint(const ImVec2& p1, const ImVec2& p2, const ImVec2& p3, const ImVec2& p4, const ImVec2& p, int num_segments);       // For curves with explicit number of segments
+IMGUI_API ImVec2     ImBezierClosestPointCasteljau(const ImVec2& p1, const ImVec2& p2, const ImVec2& p3, const ImVec2& p4, const ImVec2& p, float tess_tol);// For auto-tessellated curves you can use tess_tol = style.CurveTessellationTol
 IMGUI_API ImVec2     ImLineClosestPoint(const ImVec2& a, const ImVec2& b, const ImVec2& p);
 IMGUI_API bool       ImTriangleContainsPoint(const ImVec2& a, const ImVec2& b, const ImVec2& c, const ImVec2& p);
 IMGUI_API ImVec2     ImTriangleClosestPoint(const ImVec2& a, const ImVec2& b, const ImVec2& c, const ImVec2& p);
@@ -466,9 +477,8 @@ struct IMGUI_API ImRect
 inline bool     ImBitArrayTestBit(const ImU32* arr, int n)      { ImU32 mask = (ImU32)1 << (n & 31); return (arr[n >> 5] & mask) != 0; }
 inline void     ImBitArrayClearBit(ImU32* arr, int n)           { ImU32 mask = (ImU32)1 << (n & 31); arr[n >> 5] &= ~mask; }
 inline void     ImBitArraySetBit(ImU32* arr, int n)             { ImU32 mask = (ImU32)1 << (n & 31); arr[n >> 5] |= mask; }
-inline void     ImBitArraySetBitRange(ImU32* arr, int n, int n2) // Works on range [n..n2)
+inline void     ImBitArraySetBitRange(ImU32* arr, int n, int n2)
 {
-    n2--;
     while (n <= n2)
     {
         int a_mod = (n & 31);
@@ -486,12 +496,11 @@ struct IMGUI_API ImBitArray
 {
     ImU32           Storage[(BITCOUNT + 31) >> 5];
     ImBitArray()                                { }
-    void            ClearAllBits()              { memset(Storage, 0, sizeof(Storage)); }
-    void            SetAllBits()                { memset(Storage, 255, sizeof(Storage)); }
+    void            ClearBits()                 { memset(Storage, 0, sizeof(Storage)); }
     bool            TestBit(int n) const        { IM_ASSERT(n < BITCOUNT); return ImBitArrayTestBit(Storage, n); }
     void            SetBit(int n)               { IM_ASSERT(n < BITCOUNT); ImBitArraySetBit(Storage, n); }
     void            ClearBit(int n)             { IM_ASSERT(n < BITCOUNT); ImBitArrayClearBit(Storage, n); }
-    void            SetBitRange(int n, int n2)  { ImBitArraySetBitRange(Storage, n, n2); } // Works on range [n..n2)
+    void            SetBitRange(int n1, int n2) { ImBitArraySetBitRange(Storage, n1, n2); }
 };
 
 // Helper: ImBitVector
@@ -1002,7 +1011,10 @@ enum ImGuiNextWindowDataFlags_
     ImGuiNextWindowDataFlags_HasSizeConstraint  = 1 << 4,
     ImGuiNextWindowDataFlags_HasFocus           = 1 << 5,
     ImGuiNextWindowDataFlags_HasBgAlpha         = 1 << 6,
-    ImGuiNextWindowDataFlags_HasScroll          = 1 << 7
+    ImGuiNextWindowDataFlags_HasScroll          = 1 << 7,
+    ImGuiNextWindowDataFlags_HasViewport        = 1 << 8,
+    ImGuiNextWindowDataFlags_HasDock            = 1 << 9,
+    ImGuiNextWindowDataFlags_HasWindowClass     = 1 << 10
 };
 
 // Storage for SetNexWindow** functions
@@ -1012,17 +1024,22 @@ struct ImGuiNextWindowData
     ImGuiCond                   PosCond;
     ImGuiCond                   SizeCond;
     ImGuiCond                   CollapsedCond;
+    ImGuiCond                   DockCond;
     ImVec2                      PosVal;
     ImVec2                      PosPivotVal;
     ImVec2                      SizeVal;
     ImVec2                      ContentSizeVal;
     ImVec2                      ScrollVal;
+    bool                        PosUndock;
     bool                        CollapsedVal;
     ImRect                      SizeConstraintRect;
     ImGuiSizeCallback           SizeCallback;
     void*                       SizeCallbackUserData;
     float                       BgAlphaVal;             // Override background alpha
-    ImVec2                      MenuBarOffsetMinVal;    // *Always on* This is not exposed publicly, so we don't clear it.
+    ImGuiID                     ViewportId;
+    ImGuiID                     DockId;
+    ImGuiWindowClass            WindowClass;
+    ImVec2                      MenuBarOffsetMinVal;    // (Always on) This is not exposed publicly, so we don't clear it and it doesn't have a corresponding flag (could we? for consistency?)
 
     ImGuiNextWindowData()       { memset(this, 0, sizeof(*this)); }
     inline void ClearFlags()    { Flags = ImGuiNextWindowDataFlags_None; }
@@ -1131,7 +1148,113 @@ struct ImGuiOldColumns
 //-----------------------------------------------------------------------------
 
 #ifdef IMGUI_HAS_DOCK
-// <this is filled in 'docking' branch>
+
+// Extend ImGuiDockNodeFlags_
+enum ImGuiDockNodeFlagsPrivate_
+{
+    // [Internal]
+    ImGuiDockNodeFlags_DockSpace                = 1 << 10,  // Local, Saved  // A dockspace is a node that occupy space within an existing user window. Otherwise the node is floating and create its own window.
+    ImGuiDockNodeFlags_CentralNode              = 1 << 11,  // Local, Saved  // The central node has 2 main properties: stay visible when empty, only use "remaining" spaces from its neighbor.
+    ImGuiDockNodeFlags_NoTabBar                 = 1 << 12,  // Local, Saved  // Tab bar is completely unavailable. No triangle in the corner to enable it back.
+    ImGuiDockNodeFlags_HiddenTabBar             = 1 << 13,  // Local, Saved  // Tab bar is hidden, with a triangle in the corner to show it again (NB: actual tab-bar instance may be destroyed as this is only used for single-window tab bar)
+    ImGuiDockNodeFlags_NoWindowMenuButton       = 1 << 14,  // Local, Saved  // Disable window/docking menu (that one that appears instead of the collapse button)
+    ImGuiDockNodeFlags_NoCloseButton            = 1 << 15,  // Local, Saved  //
+    ImGuiDockNodeFlags_NoDocking                = 1 << 16,  // Local, Saved  // Disable any form of docking in this dockspace or individual node. (On a whole dockspace, this pretty much defeat the purpose of using a dockspace at all). Note: when turned on, existing docked nodes will be preserved.
+    ImGuiDockNodeFlags_NoDockingSplitMe         = 1 << 17,  // [EXPERIMENTAL] Prevent another window/node from splitting this node.
+    ImGuiDockNodeFlags_NoDockingSplitOther      = 1 << 18,  // [EXPERIMENTAL] Prevent this node from splitting another window/node.
+    ImGuiDockNodeFlags_NoDockingOverMe          = 1 << 19,  // [EXPERIMENTAL] Prevent another window/node to be docked over this node.
+    ImGuiDockNodeFlags_NoDockingOverOther       = 1 << 20,  // [EXPERIMENTAL] Prevent this node to be docked over another window/node.
+    ImGuiDockNodeFlags_NoResizeX                = 1 << 21,  // [EXPERIMENTAL]
+    ImGuiDockNodeFlags_NoResizeY                = 1 << 22,  // [EXPERIMENTAL]
+    ImGuiDockNodeFlags_SharedFlagsInheritMask_  = ~0,
+    ImGuiDockNodeFlags_NoResizeFlagsMask_       = ImGuiDockNodeFlags_NoResize | ImGuiDockNodeFlags_NoResizeX | ImGuiDockNodeFlags_NoResizeY,
+    ImGuiDockNodeFlags_LocalFlagsMask_          = ImGuiDockNodeFlags_NoSplit | ImGuiDockNodeFlags_NoResizeFlagsMask_ | ImGuiDockNodeFlags_AutoHideTabBar | ImGuiDockNodeFlags_DockSpace | ImGuiDockNodeFlags_CentralNode | ImGuiDockNodeFlags_NoTabBar | ImGuiDockNodeFlags_HiddenTabBar | ImGuiDockNodeFlags_NoWindowMenuButton | ImGuiDockNodeFlags_NoCloseButton | ImGuiDockNodeFlags_NoDocking,
+    ImGuiDockNodeFlags_LocalFlagsTransferMask_  = ImGuiDockNodeFlags_LocalFlagsMask_ & ~ImGuiDockNodeFlags_DockSpace,  // When splitting those flags are moved to the inheriting child, never duplicated
+    ImGuiDockNodeFlags_SavedFlagsMask_          = ImGuiDockNodeFlags_NoResizeFlagsMask_ | ImGuiDockNodeFlags_DockSpace | ImGuiDockNodeFlags_CentralNode | ImGuiDockNodeFlags_NoTabBar | ImGuiDockNodeFlags_HiddenTabBar | ImGuiDockNodeFlags_NoWindowMenuButton | ImGuiDockNodeFlags_NoCloseButton | ImGuiDockNodeFlags_NoDocking
+};
+
+// Store the source authority (dock node vs window) of a field
+enum ImGuiDataAuthority_
+{
+    ImGuiDataAuthority_Auto,
+    ImGuiDataAuthority_DockNode,
+    ImGuiDataAuthority_Window
+};
+
+enum ImGuiDockNodeState
+{
+    ImGuiDockNodeState_Unknown,
+    ImGuiDockNodeState_HostWindowHiddenBecauseSingleWindow,
+    ImGuiDockNodeState_HostWindowHiddenBecauseWindowsAreResizing,
+    ImGuiDockNodeState_HostWindowVisible
+};
+
+// sizeof() 116~160
+struct ImGuiDockNode
+{
+    ImGuiID                 ID;
+    ImGuiDockNodeFlags      SharedFlags;                // Flags shared by all nodes of a same dockspace hierarchy (inherited from the root node)
+    ImGuiDockNodeFlags      LocalFlags;                 // Flags specific to this node
+    ImGuiDockNodeState      State;
+    ImGuiDockNode*          ParentNode;
+    ImGuiDockNode*          ChildNodes[2];              // [Split node only] Child nodes (left/right or top/bottom). Consider switching to an array.
+    ImVector<ImGuiWindow*>  Windows;                    // Note: unordered list! Iterate TabBar->Tabs for user-order.
+    ImGuiTabBar*            TabBar;
+    ImVec2                  Pos;                        // Current position
+    ImVec2                  Size;                       // Current size
+    ImVec2                  SizeRef;                    // [Split node only] Last explicitly written-to size (overridden when using a splitter affecting the node), used to calculate Size.
+    ImGuiAxis               SplitAxis;                  // [Split node only] Split axis (X or Y)
+    ImGuiWindowClass        WindowClass;                // [Root node only]
+
+    ImGuiWindow*            HostWindow;
+    ImGuiWindow*            VisibleWindow;              // Generally point to window which is ID is == SelectedTabID, but when CTRL+Tabbing this can be a different window.
+    ImGuiDockNode*          CentralNode;                // [Root node only] Pointer to central node.
+    ImGuiDockNode*          OnlyNodeWithWindows;        // [Root node only] Set when there is a single visible node within the hierarchy.
+    int                     LastFrameAlive;             // Last frame number the node was updated or kept alive explicitly with DockSpace() + ImGuiDockNodeFlags_KeepAliveOnly
+    int                     LastFrameActive;            // Last frame number the node was updated.
+    int                     LastFrameFocused;           // Last frame number the node was focused.
+    ImGuiID                 LastFocusedNodeId;          // [Root node only] Which of our child docking node (any ancestor in the hierarchy) was last focused.
+    ImGuiID                 SelectedTabId;              // [Leaf node only] Which of our tab/window is selected.
+    ImGuiID                 WantCloseTabId;             // [Leaf node only] Set when closing a specific tab/window.
+    ImGuiDataAuthority      AuthorityForPos         :3;
+    ImGuiDataAuthority      AuthorityForSize        :3;
+    ImGuiDataAuthority      AuthorityForViewport    :3;
+    bool                    IsVisible               :1; // Set to false when the node is hidden (usually disabled as it has no active window)
+    bool                    IsFocused               :1;
+    bool                    HasCloseButton          :1;
+    bool                    HasWindowMenuButton     :1;
+    bool                    EnableCloseButton       :1;
+    bool                    WantCloseAll            :1; // Set when closing all tabs at once.
+    bool                    WantLockSizeOnce        :1;
+    bool                    WantMouseMove           :1; // After a node extraction we need to transition toward moving the newly created host window
+    bool                    WantHiddenTabBarUpdate  :1;
+    bool                    WantHiddenTabBarToggle  :1;
+    bool                    MarkedForPosSizeWrite   :1; // Update by DockNodeTreeUpdatePosSize() write-filtering
+
+    ImGuiDockNode(ImGuiID id);
+    ~ImGuiDockNode();
+    bool                    IsRootNode() const      { return ParentNode == NULL; }
+    bool                    IsDockSpace() const     { return (LocalFlags & ImGuiDockNodeFlags_DockSpace) != 0; }
+    bool                    IsFloatingNode() const  { return ParentNode == NULL && (LocalFlags & ImGuiDockNodeFlags_DockSpace) == 0; }
+    bool                    IsCentralNode() const   { return (LocalFlags & ImGuiDockNodeFlags_CentralNode) != 0; }
+    bool                    IsHiddenTabBar() const  { return (LocalFlags & ImGuiDockNodeFlags_HiddenTabBar) != 0; } // Hidden tab bar can be shown back by clicking the small triangle
+    bool                    IsNoTabBar() const      { return (LocalFlags & ImGuiDockNodeFlags_NoTabBar) != 0; }     // Never show a tab bar
+    bool                    IsSplitNode() const     { return ChildNodes[0] != NULL; }
+    bool                    IsLeafNode() const      { return ChildNodes[0] == NULL; }
+    bool                    IsEmpty() const         { return ChildNodes[0] == NULL && Windows.Size == 0; }
+    ImGuiDockNodeFlags      GetMergedFlags() const  { return SharedFlags | LocalFlags; }
+    ImRect                  Rect() const            { return ImRect(Pos.x, Pos.y, Pos.x + Size.x, Pos.y + Size.y); }
+};
+
+struct ImGuiDockContext
+{
+    ImGuiStorage                    Nodes;          // Map ID -> ImGuiDockNode*: Active nodes
+    ImVector<ImGuiDockRequest>      Requests;
+    ImVector<ImGuiDockNodeSettings> NodesSettings;
+    bool                            WantFullRebuild;
+    ImGuiDockContext()              { WantFullRebuild = false; }
+};
+
 #endif // #ifdef IMGUI_HAS_DOCK
 
 //-----------------------------------------------------------------------------
@@ -1139,7 +1262,38 @@ struct ImGuiOldColumns
 //-----------------------------------------------------------------------------
 
 #ifdef IMGUI_HAS_VIEWPORT
-// <this is filled in 'docking' branch>
+
+// ImGuiViewport Private/Internals fields (cardinal sin: we are using inheritance!)
+// Note that every instance of ImGuiViewport is in fact a ImGuiViewportP.
+struct ImGuiViewportP : public ImGuiViewport
+{
+    int                 Idx;
+    int                 LastFrameActive;          // Last frame number this viewport was activated by a window
+    int                 LastFrameDrawLists[2];    // Last frame number the background (0) and foreground (1) draw lists were used
+    int                 LastFrontMostStampCount;  // Last stamp number from when a window hosted by this viewport was made front-most (by comparing this value between two viewport we have an implicit viewport z-order
+    ImGuiID             LastNameHash;
+    ImVec2              LastPos;
+    float               Alpha;                    // Window opacity (when dragging dockable windows/viewports we make them transparent)
+    float               LastAlpha;
+    short               PlatformMonitor;
+    bool                PlatformWindowCreated;
+    ImGuiWindow*        Window;                   // Set when the viewport is owned by a window (and ImGuiViewportFlags_CanHostOtherWindows is NOT set)
+    ImDrawList*         DrawLists[2];             // Convenience background (0) and foreground (1) draw lists. We use them to draw software mouser cursor when io.MouseDrawCursor is set and to draw most debug overlays.
+    ImDrawData          DrawDataP;
+    ImDrawDataBuilder   DrawDataBuilder;
+    ImVec2              LastPlatformPos;
+    ImVec2              LastPlatformSize;
+    ImVec2              LastRendererSize;
+    ImVec2              CurrWorkOffsetMin;        // Work area top-left offset being increased during the frame
+    ImVec2              CurrWorkOffsetMax;        // Work area bottom-right offset being decreased during the frame
+
+    ImGuiViewportP()                { Idx = -1; LastFrameActive = LastFrameDrawLists[0] = LastFrameDrawLists[1] = LastFrontMostStampCount = -1; LastNameHash = 0; Alpha = LastAlpha = 1.0f; PlatformMonitor = -1; PlatformWindowCreated = false; Window = NULL; DrawLists[0] = DrawLists[1] = NULL; LastPlatformPos = LastPlatformSize = LastRendererSize = ImVec2(FLT_MAX, FLT_MAX); }
+    ~ImGuiViewportP()               { if (DrawLists[0]) IM_DELETE(DrawLists[0]); if (DrawLists[1]) IM_DELETE(DrawLists[1]); }
+    ImRect  GetMainRect() const     { return ImRect(Pos.x, Pos.y, Pos.x + Size.x, Pos.y + Size.y); }
+    ImRect  GetWorkRect() const     { return ImRect(Pos.x + WorkOffsetMin.x, Pos.y + WorkOffsetMin.y, Pos.x + Size.x + WorkOffsetMax.x, Pos.y + Size.y + WorkOffsetMax.y); }
+    void    ClearRequestFlags()     { PlatformRequestClose = PlatformRequestMove = PlatformRequestResize = false; }
+};
+
 #endif // #ifdef IMGUI_HAS_VIEWPORT
 
 //-----------------------------------------------------------------------------
@@ -1152,12 +1306,17 @@ struct ImGuiOldColumns
 struct ImGuiWindowSettings
 {
     ImGuiID     ID;
-    ImVec2ih    Pos;
+    ImVec2ih    Pos;            // NB: Settings position are stored RELATIVE to the viewport! Whereas runtime ones are absolute positions.
     ImVec2ih    Size;
+    ImVec2ih    ViewportPos;
+    ImGuiID     ViewportId;
+    ImGuiID     DockId;         // ID of last known DockNode (even if the DockNode is invisible because it has only 1 active window), or 0 if none.
+    ImGuiID     ClassId;        // ID of window class if specified
+    short       DockOrder;      // Order of the last time the window was visible within its DockNode. This is used to reorder windows that are reappearing on the same frame. Same value between windows that were active and windows that were none are possible.
     bool        Collapsed;
     bool        WantApply;      // Set when loaded from .ini data (to enable merging/loading .ini data into an already running context)
 
-    ImGuiWindowSettings()       { memset(this, 0, sizeof(*this)); }
+    ImGuiWindowSettings()       { memset(this, 0, sizeof(*this)); DockOrder = -1; }
     char* GetName()             { return (char*)(this + 1); }
 };
 
@@ -1187,6 +1346,7 @@ struct ImGuiMetricsConfig
     bool        ShowTablesRects;
     bool        ShowDrawCmdMesh;
     bool        ShowDrawCmdBoundingBoxes;
+    bool        ShowDockingNodes;
     int         ShowWindowsRectsType;
     int         ShowTablesRectsType;
 
@@ -1197,6 +1357,7 @@ struct ImGuiMetricsConfig
         ShowTablesRects = false;
         ShowDrawCmdMesh = true;
         ShowDrawCmdBoundingBoxes = true;
+        ShowDockingNodes = false;
         ShowWindowsRectsType = -1;
         ShowTablesRectsType = -1;
     }
@@ -1243,7 +1404,10 @@ struct ImGuiContext
     bool                    Initialized;
     bool                    FontAtlasOwnedByContext;            // IO.Fonts-> is owned by the ImGuiContext and will be destructed along with it.
     ImGuiIO                 IO;
+    ImGuiPlatformIO         PlatformIO;
     ImGuiStyle              Style;
+    ImGuiConfigFlags        ConfigFlagsCurrFrame;               // = g.IO.ConfigFlags at the time of NewFrame()
+    ImGuiConfigFlags        ConfigFlagsLastFrame;
     ImFont*                 Font;                               // (Shortcut) == FontStack.empty() ? IO.Font : FontStack.back()
     float                   FontSize;                           // (Shortcut) == FontBaseSize * g.CurrentWindow->FontWindowScale == window->FontSize(). Text height for current window.
     float                   FontBaseSize;                       // (Shortcut) == IO.FontGlobalScale * Font->Scale * Font->FontSize. Base text height.
@@ -1251,6 +1415,7 @@ struct ImGuiContext
     double                  Time;
     int                     FrameCount;
     int                     FrameCountEnded;
+    int                     FrameCountPlatformEnded;
     int                     FrameCountRendered;
     bool                    WithinFrameScope;                   // Set by NewFrame(), cleared by EndFrame()
     bool                    WithinFrameScopeWithImplicitWindow; // Set by NewFrame(), cleared by EndFrame() when the implicit debug window has been pushed
@@ -1271,17 +1436,17 @@ struct ImGuiContext
     ImGuiWindow*            HoveredWindow;                      // Window the mouse is hovering. Will typically catch mouse inputs.
     ImGuiWindow*            HoveredRootWindow;                  // == HoveredWindow ? HoveredWindow->RootWindow : NULL, merely a shortcut to avoid null test in some situation.
     ImGuiWindow*            HoveredWindowUnderMovingWindow;     // Hovered window ignoring MovingWindow. Only set if MovingWindow is set.
+    ImGuiDockNode*          HoveredDockNode;                    // Hovered dock node.
     ImGuiWindow*            MovingWindow;                       // Track the window we clicked on (in order to preserve focus). The actual window that is moved is generally MovingWindow->RootWindow.
+    ImGuiWindow*            LastBeginWindow;                    // Track the last window we called Begin() on, this is used to easily access it even if Begin() returned false.
     ImGuiWindow*            WheelingWindow;                     // Track the window we started mouse-wheeling on. Until a timer elapse or mouse has moved, generally keep scrolling the same window even if during the course of scrolling the mouse ends up hovering a child window.
     ImVec2                  WheelingWindowRefMousePos;
     float                   WheelingWindowTimer;
 
     // Item/widgets state and tracking information
-    ImGuiID                 HoveredId;                          // Hovered widget, filled during the frame
+    ImGuiID                 HoveredId;                          // Hovered widget
     ImGuiID                 HoveredIdPreviousFrame;
     bool                    HoveredIdAllowOverlap;
-    bool                    HoveredIdUsingMouseWheel;           // Hovered widget will use mouse wheel. Blocks scrolling the underlying window.
-    bool                    HoveredIdPreviousFrameUsingMouseWheel;
     bool                    HoveredIdDisabled;                  // At least one widget passed the rect test, but has been discarded by disabled flag or popup inhibit. May be true even if HoveredId == 0.
     float                   HoveredIdTimer;                     // Measure contiguous hovering time
     float                   HoveredIdNotActiveTimer;            // Measure contiguous hovering time where the item has not been active
@@ -1294,7 +1459,6 @@ struct ImGuiContext
     bool                    ActiveIdHasBeenPressedBefore;       // Track whether the active id led to a press (this is to allow changing between PressOnClick and PressOnRelease without pressing twice). Used by range_select branch.
     bool                    ActiveIdHasBeenEditedBefore;        // Was the value associated to the widget Edited over the course of the Active state.
     bool                    ActiveIdHasBeenEditedThisFrame;
-    bool                    ActiveIdUsingMouseWheel;            // Active widget will want to read mouse wheel. Blocks scrolling the underlying window.
     ImU32                   ActiveIdUsingNavDirMask;            // Active widget will want to read those nav move requests (e.g. can activate a button and move away from it)
     ImU32                   ActiveIdUsingNavInputMask;          // Active widget will want to read those nav inputs.
     ImU64                   ActiveIdUsingKeyInputMask;          // Active widget will want to read those key inputs. When we grow the ImGuiKey enum we'll need to either to order the enum to make useful keys come first, either redesign this into e.g. a small array.
@@ -1323,6 +1487,14 @@ struct ImGuiContext
     ImVector<ImGuiPopupData>OpenPopupStack;                     // Which popups are open (persistent)
     ImVector<ImGuiPopupData>BeginPopupStack;                    // Which level of BeginPopup() we are in (reset every frame)
 
+    // Viewports
+    ImVector<ImGuiViewportP*> Viewports;                        // Active viewports (always 1+, and generally 1 unless multi-viewports are enabled). Each viewports hold their copy of ImDrawData.
+    float                   CurrentDpiScale;                    // == CurrentViewport->DpiScale
+    ImGuiViewportP*         CurrentViewport;                    // We track changes of viewport (happening in Begin) so we can call Platform_OnChangedViewport()
+    ImGuiViewportP*         MouseViewport;
+    ImGuiViewportP*         MouseLastHoveredViewport;           // Last known viewport that was hovered by mouse (even if we are not hovering any viewport any more) + honoring the _NoInputs flag.
+    int                     ViewportFrontMostStampCount;        // Every time the front-most window changes, we stamp its viewport with an incrementing counter
+
     // Gamepad/keyboard Navigation
     ImGuiWindow*            NavWindow;                          // Focused window for navigation. Could be called 'FocusWindow'
     ImGuiID                 NavId;                              // Focused item for navigation
@@ -1380,11 +1552,7 @@ struct ImGuiContext
     bool                    FocusTabPressed;                    //
 
     // Render
-    ImDrawData              DrawData;                           // Main ImDrawData instance to pass render information to the user
-    ImDrawDataBuilder       DrawDataBuilder;
     float                   DimBgRatio;                         // 0.0..1.0 animation when fading in a dimming background (for modal window and CTRL+TAB list)
-    ImDrawList              BackgroundDrawList;                 // First draw list to be rendered.
-    ImDrawList              ForegroundDrawList;                 // Last draw list to be rendered. This is where we the render software mouse cursor (if io.MouseDrawCursor is set) and most debug overlays.
     ImGuiMouseCursor        MouseCursor;
 
     // Drag and Drop
@@ -1443,8 +1611,13 @@ struct ImGuiContext
     // Platform support
     ImVec2                  PlatformImePos;                     // Cursor position request & last passed to the OS Input Method Editor
     ImVec2                  PlatformImeLastPos;
+    ImGuiViewportP*         PlatformImePosViewport;
     char                    PlatformLocaleDecimalPoint;         // '.' or *localeconv()->decimal_point
 
+    // Extensions
+    // FIXME: We could provide an API to register one slot in an array held in ImGuiContext?
+    ImGuiDockContext        DockContext;
+
     // Settings
     bool                    SettingsLoaded;
     float                   SettingsDirtyTimer;                 // Save .ini Settings to memory when time reaches zero
@@ -1468,6 +1641,7 @@ struct ImGuiContext
     // Debug Tools
     bool                    DebugItemPickerActive;              // Item picker is active (started with DebugStartItemPicker())
     ImGuiID                 DebugItemPickerBreakId;             // Will call IM_DEBUG_BREAK() when encountering this id
+    int                     DebugBeginReturnValueCullDepth;     // Cycle between 0..9 then wrap around.
     ImGuiMetricsConfig      DebugMetricsConfig;
 
     // Misc
@@ -1479,16 +1653,17 @@ struct ImGuiContext
     int                     WantTextInputNextFrame;
     char                    TempBuffer[1024 * 3 + 1];           // Temporary text buffer
 
-    ImGuiContext(ImFontAtlas* shared_font_atlas) : BackgroundDrawList(&DrawListSharedData), ForegroundDrawList(&DrawListSharedData)
+    ImGuiContext(ImFontAtlas* shared_font_atlas)
     {
         Initialized = false;
+        ConfigFlagsCurrFrame = ConfigFlagsLastFrame = ImGuiConfigFlags_None;
         FontAtlasOwnedByContext = shared_font_atlas ? false : true;
         Font = NULL;
         FontSize = FontBaseSize = 0.0f;
         IO.Fonts = shared_font_atlas ? shared_font_atlas : IM_NEW(ImFontAtlas)();
         Time = 0.0f;
         FrameCount = 0;
-        FrameCountEnded = FrameCountRendered = -1;
+        FrameCountEnded = FrameCountPlatformEnded = FrameCountRendered = -1;
         WithinFrameScope = WithinFrameScopeWithImplicitWindow = WithinEndChild = false;
         GcCompactAll = false;
         TestEngineHookItems = false;
@@ -1500,13 +1675,14 @@ struct ImGuiContext
         HoveredWindow = NULL;
         HoveredRootWindow = NULL;
         HoveredWindowUnderMovingWindow = NULL;
+        HoveredDockNode = NULL;
         MovingWindow = NULL;
+        LastBeginWindow = NULL;
         WheelingWindow = NULL;
         WheelingWindowTimer = 0.0f;
 
         HoveredId = HoveredIdPreviousFrame = 0;
         HoveredIdAllowOverlap = false;
-        HoveredIdUsingMouseWheel = HoveredIdPreviousFrameUsingMouseWheel = false;
         HoveredIdDisabled = false;
         HoveredIdTimer = HoveredIdNotActiveTimer = 0.0f;
         ActiveId = 0;
@@ -1518,7 +1694,6 @@ struct ImGuiContext
         ActiveIdHasBeenPressedBefore = false;
         ActiveIdHasBeenEditedBefore = false;
         ActiveIdHasBeenEditedThisFrame = false;
-        ActiveIdUsingMouseWheel = false;
         ActiveIdUsingNavDirMask = 0x00;
         ActiveIdUsingNavInputMask = 0x00;
         ActiveIdUsingKeyInputMask = 0x00;
@@ -1533,6 +1708,11 @@ struct ImGuiContext
         LastActiveId = 0;
         LastActiveIdTimer = 0.0f;
 
+        CurrentDpiScale = 0.0f;
+        CurrentViewport = NULL;
+        MouseViewport = MouseLastHoveredViewport = NULL;
+        ViewportFrontMostStampCount = 0;
+
         NavWindow = NULL;
         NavId = NavFocusScopeId = NavActivateId = NavActivateDownId = NavActivatePressedId = NavInputId = 0;
         NavJustTabbedId = NavJustMovedToId = NavJustMovedToFocusScopeId = NavNextActivateId = 0;
@@ -1568,8 +1748,6 @@ struct ImGuiContext
         FocusTabPressed = false;
 
         DimBgRatio = 0.0f;
-        BackgroundDrawList._OwnerName = "##Background"; // Give it a name for debugging
-        ForegroundDrawList._OwnerName = "##Foreground"; // Give it a name for debugging
         MouseCursor = ImGuiMouseCursor_Arrow;
 
         DragDropActive = DragDropWithinSource = DragDropWithinTarget = false;
@@ -1602,6 +1780,7 @@ struct ImGuiContext
         TooltipSlowDelay = 0.50f;
 
         PlatformImePos = PlatformImeLastPos = ImVec2(FLT_MAX, FLT_MAX);
+        PlatformImePosViewport = 0;
         PlatformLocaleDecimalPoint = '.';
 
         SettingsLoaded = false;
@@ -1617,6 +1796,7 @@ struct ImGuiContext
 
         DebugItemPickerActive = false;
         DebugItemPickerBreakId = 0;
+        DebugBeginReturnValueCullDepth = -1;
 
         memset(FramerateSecPerFrame, 0, sizeof(FramerateSecPerFrame));
         FramerateSecPerFrameIdx = 0;
@@ -1639,8 +1819,7 @@ struct IMGUI_API ImGuiWindowTempData
     ImVec2                  CursorPos;              // Current emitting position, in absolute coordinates.
     ImVec2                  CursorPosPrevLine;
     ImVec2                  CursorStartPos;         // Initial position after Begin(), generally ~ window position + WindowPadding.
-    ImVec2                  CursorMaxPos;           // Used to implicitly calculate ContentSize at the beginning of next frame, for scrolling range and auto-resize. Always growing during the frame.
-    ImVec2                  IdealMaxPos;            // Used to implicitly calculate ContentSizeIdeal at the beginning of next frame, for auto-resize only. Always growing during the frame.
+    ImVec2                  CursorMaxPos;           // Used to implicitly calculate the size of our contents, always growing during the frame. Used to calculate window->ContentSize at the beginning of next frame
     ImVec2                  CurrLineSize;
     ImVec2                  PrevLineSize;
     float                   CurrLineTextBaseOffset; // Baseline offset (0.0f by default on a new line, generally == style.FramePadding.y when a framed item has been added).
@@ -1693,12 +1872,16 @@ struct IMGUI_API ImGuiWindow
 {
     char*                   Name;                               // Window name, owned by the window.
     ImGuiID                 ID;                                 // == ImHashStr(Name)
-    ImGuiWindowFlags        Flags;                              // See enum ImGuiWindowFlags_
+    ImGuiWindowFlags        Flags, FlagsPreviousFrame;          // See enum ImGuiWindowFlags_
+    ImGuiWindowClass        WindowClass;                        // Advanced users only. Set with SetNextWindowClass()
+    ImGuiViewportP*         Viewport;                           // Always set in Begin(), only inactive windows may have a NULL value here
+    ImGuiID                 ViewportId;                         // We backup the viewport id (since the viewport may disappear or never be created if the window is inactive)
+    ImVec2                  ViewportPos;                        // We backup the viewport position (since the viewport may disappear or never be created if the window is inactive)
+    int                     ViewportAllowPlatformMonitorExtend; // Reset to -1 every frame (index is guaranteed to be valid between NewFrame..EndFrame), only used in the Appearing frame of a tooltip/popup to enforce clamping to a given monitor
     ImVec2                  Pos;                                // Position (always rounded-up to nearest pixel)
     ImVec2                  Size;                               // Current size (==SizeFull or collapsed title bar size)
     ImVec2                  SizeFull;                           // Size when non collapsed
     ImVec2                  ContentSize;                        // Size of contents/scrollable client area (calculated from the extents reach of the cursor) from previous frame. Does not include window decoration or window padding.
-    ImVec2                  ContentSizeIdeal;
     ImVec2                  ContentSizeExplicit;                // Size of contents/scrollable client area explicitly request by the user via SetNextWindowContentSize().
     ImVec2                  WindowPadding;                      // Window padding at the time of Begin().
     float                   WindowRounding;                     // Window rounding at the time of Begin(). May be clamped lower to avoid rendering artifacts with title bar, menu bar etc.
@@ -1713,6 +1896,7 @@ struct IMGUI_API ImGuiWindow
     ImVec2                  ScrollTargetEdgeSnapDist;           // 0.0f = no snapping, >0.0f snapping threshold
     ImVec2                  ScrollbarSizes;                     // Size taken by each scrollbars on their smaller axis. Pay attention! ScrollbarSizes.x == width of the vertical scrollbar, ScrollbarSizes.y = height of the horizontal scrollbar.
     bool                    ScrollbarX, ScrollbarY;             // Are scrollbars visible?
+    bool                    ViewportOwned;
     bool                    Active;                             // Set to true on Begin(), unless Collapsed
     bool                    WasActive;
     bool                    WriteAccessed;                      // Set to true when any widget access the current window
@@ -1732,12 +1916,12 @@ struct IMGUI_API ImGuiWindow
     ImS8                    AutoFitChildAxises;
     bool                    AutoFitOnlyGrows;
     ImGuiDir                AutoPosLastDirection;
-    ImS8                    HiddenFramesCanSkipItems;           // Hide the window for N frames
-    ImS8                    HiddenFramesCannotSkipItems;        // Hide the window for N frames while allowing items to be submitted so we can measure their size
-    ImS8                    HiddenFramesForRenderOnly;          // Hide the window until frame N at Render() time only
-    ImGuiCond               SetWindowPosAllowFlags : 8;         // store acceptable condition flags for SetNextWindowPos() use.
-    ImGuiCond               SetWindowSizeAllowFlags : 8;        // store acceptable condition flags for SetNextWindowSize() use.
-    ImGuiCond               SetWindowCollapsedAllowFlags : 8;   // store acceptable condition flags for SetNextWindowCollapsed() use.
+    int                     HiddenFramesCanSkipItems;           // Hide the window for N frames
+    int                     HiddenFramesCannotSkipItems;        // Hide the window for N frames while allowing items to be submitted so we can measure their size
+    ImGuiCond               SetWindowPosAllowFlags;             // store acceptable condition flags for SetNextWindowPos() use.
+    ImGuiCond               SetWindowSizeAllowFlags;            // store acceptable condition flags for SetNextWindowSize() use.
+    ImGuiCond               SetWindowCollapsedAllowFlags;       // store acceptable condition flags for SetNextWindowCollapsed() use.
+    ImGuiCond               SetWindowDockAllowFlags;            // store acceptable condition flags for SetNextWindowDock() use.
     ImVec2                  SetWindowPosVal;                    // store window position when using a non-zero Pivot (position set needs to be processed when we know the window size)
     ImVec2                  SetWindowPosPivot;                  // store window pivot for positioning. ImVec2(0, 0) when positioning from top-left corner; ImVec2(0.5f, 0.5f) for centering; ImVec2(1, 1) for bottom right.
 
@@ -1757,17 +1941,20 @@ struct IMGUI_API ImGuiWindow
     ImVec2ih                HitTestHoleOffset;
 
     int                     LastFrameActive;                    // Last frame number the window was Active.
+    int                     LastFrameJustFocused;               // Last frame number the window was made Focused.
     float                   LastTimeActive;                     // Last timestamp the window was Active (using float as we don't need high precision there)
     float                   ItemWidthDefault;
     ImGuiStorage            StateStorage;
     ImVector<ImGuiOldColumns> ColumnsStorage;
     float                   FontWindowScale;                    // User scale multiplier per-window, via SetWindowFontScale()
+    float                   FontDpiScale;
     int                     SettingsOffset;                     // Offset into SettingsWindows[] (offsets are always valid as we only grow the array from the back)
 
     ImDrawList*             DrawList;                           // == &DrawListInst (for backward compatibility reason with code using imgui_internal.h we keep this a pointer)
     ImDrawList              DrawListInst;
     ImGuiWindow*            ParentWindow;                       // If we are a child _or_ popup window, this is pointing to our parent. Otherwise NULL.
     ImGuiWindow*            RootWindow;                         // Point to ourself or first ancestor that is not a child window == Top-level window.
+    ImGuiWindow*            RootWindowDockStop;                 // Point to ourself or first ancestor that is not a child window. Doesn't cross through dock nodes. We use this so IsWindowFocused() can behave consistently regardless of docking state.
     ImGuiWindow*            RootWindowForTitleBarHighlight;     // Point to ourself or first ancestor which will display TitleBgActive color when this window is active.
     ImGuiWindow*            RootWindowForNav;                   // Point to ourself or first ancestor which doesn't have the NavFlattened flag.
 
@@ -1779,6 +1966,17 @@ struct IMGUI_API ImGuiWindow
     int                     MemoryDrawListVtxCapacity;
     bool                    MemoryCompacted;                    // Set when window extraneous data have been garbage collected
 
+    // Docking
+    ImGuiDockNode*          DockNode;                           // Which node are we docked into. Important: Prefer testing DockIsActive in many cases as this will still be set when the dock node is hidden.
+    ImGuiDockNode*          DockNodeAsHost;                     // Which node are we owning (for parent windows)
+    ImGuiID                 DockId;                             // Backup of last valid DockNode->ID, so single window remember their dock node id even when they are not bound any more
+    ImGuiItemStatusFlags    DockTabItemStatusFlags;
+    ImRect                  DockTabItemRect;
+    short                   DockOrder;                          // Order of the last time the window was visible within its DockNode. This is used to reorder windows that are reappearing on the same frame. Same value between windows that were active and windows that were none are possible.
+    bool                    DockIsActive        :1;             // When docking artifacts are actually visible. When this is set, DockNode is guaranteed to be != NULL. ~~ (DockNode != NULL) && (DockNode->Windows.Size > 1).
+    bool                    DockTabIsVisible    :1;             // Is our window visible this frame? ~~ is the corresponding tab selected?
+    bool                    DockTabWantClose    :1;
+
 public:
     ImGuiWindow(ImGuiContext* context, const char* name);
     ~ImGuiWindow();
@@ -1793,7 +1991,7 @@ public:
 
     // We don't use g.FontSize because the window may be != g.CurrentWidow.
     ImRect      Rect() const            { return ImRect(Pos.x, Pos.y, Pos.x + Size.x, Pos.y + Size.y); }
-    float       CalcFontSize() const    { ImGuiContext& g = *GImGui; float scale = g.FontBaseSize * FontWindowScale; if (ParentWindow) scale *= ParentWindow->FontWindowScale; return scale; }
+    float       CalcFontSize() const    { ImGuiContext& g = *GImGui; float scale = g.FontBaseSize * FontWindowScale * FontDpiScale; if (ParentWindow) scale *= ParentWindow->FontWindowScale; return scale; }
     float       TitleBarHeight() const  { ImGuiContext& g = *GImGui; return (Flags & ImGuiWindowFlags_NoTitleBar) ? 0.0f : CalcFontSize() + g.Style.FramePadding.y * 2.0f; }
     ImRect      TitleBarRect() const    { return ImRect(Pos, ImVec2(Pos.x + SizeFull.x, Pos.y + TitleBarHeight())); }
     float       MenuBarHeight() const   { ImGuiContext& g = *GImGui; return (Flags & ImGuiWindowFlags_MenuBar) ? DC.MenuBarOffset.y + CalcFontSize() + g.Style.FramePadding.y * 2.0f : 0.0f; }
@@ -1829,14 +2027,17 @@ enum ImGuiTabBarFlagsPrivate_
 enum ImGuiTabItemFlagsPrivate_
 {
     ImGuiTabItemFlags_NoCloseButton             = 1 << 20,  // Track whether p_open was set or not (we'll need this info on the next frame to recompute ContentWidth during layout)
-    ImGuiTabItemFlags_Button                    = 1 << 21   // Used by TabItemButton, change the tab item behavior to mimic a button
+    ImGuiTabItemFlags_Button                    = 1 << 21,  // Used by TabItemButton, change the tab item behavior to mimic a button
+    ImGuiTabItemFlags_Unsorted                  = 1 << 22,  // [Docking] Trailing tabs with the _Unsorted flag will be sorted based on the DockOrder of their Window.
+    ImGuiTabItemFlags_Preview                   = 1 << 23   // [Docking] Display tab shape for docking preview (height is adjusted slightly to compensate for the yet missing tab bar)
 };
 
-// Storage for one active tab item (sizeof() 28~32 bytes)
+// Storage for one active tab item (sizeof() 32~40 bytes)
 struct ImGuiTabItem
 {
     ImGuiID             ID;
     ImGuiTabItemFlags   Flags;
+    ImGuiWindow*        Window;                 // When TabItem is part of a DockNode's TabBar, we hold on to a window.
     int                 LastFrameVisible;
     int                 LastFrameSelected;      // This allows us to infer an ordered list of the last activated tabs with little maintenance
     float               Offset;                 // Position relative to beginning of tab
@@ -1889,6 +2090,8 @@ struct ImGuiTabBar
     int                 GetTabOrder(const ImGuiTabItem* tab) const  { return Tabs.index_from_ptr(tab); }
     const char*         GetTabName(const ImGuiTabItem* tab) const
     {
+        if (tab->Window)
+            return tab->Window->Name;
         IM_ASSERT(tab->NameOffset != -1 && (int)tab->NameOffset < TabsNames.Buf.Size);
         return TabsNames.Buf.Data + tab->NameOffset;
     }
@@ -1914,19 +2117,20 @@ typedef ImU8 ImGuiTableDrawChannelIdx;
 // This is in contrast with some user-facing api such as IsItemVisible() / IsRectVisible() which use "Visible" to mean "not clipped".
 struct ImGuiTableColumn
 {
-    ImGuiTableColumnFlags   Flags;                          // Flags after some patching (not directly same as provided by user). See ImGuiTableColumnFlags_
-    float                   WidthGiven;                     // Final/actual width visible == (MaxX - MinX), locked in TableUpdateLayout(). May be > WidthRequest to honor minimum width, may be < WidthRequest to honor shrinking columns down in tight space.
-    float                   MinX;                           // Absolute positions
-    float                   MaxX;
-    float                   WidthRequest;                   // Master width absolute value when !(Flags & _WidthStretch). When Stretch this is derived every frame from StretchWeight in TableUpdateLayout()
-    float                   WidthAuto;                      // Automatic width
-    float                   StretchWeight;                  // Master width weight when (Flags & _WidthStretch). Often around ~1.0f initially.
-    float                   InitStretchWeightOrWidth;       // Value passed to TableSetupColumn(). For Width it is a content width (_without padding_).
     ImRect                  ClipRect;                       // Clipping rectangle for the column
     ImGuiID                 UserID;                         // Optional, value passed to TableSetupColumn()
-    float                   WorkMinX;                       // Contents region min ~(MinX + CellPaddingX + CellSpacingX1) == cursor start position when entering column
-    float                   WorkMaxX;                       // Contents region max ~(MaxX - CellPaddingX - CellSpacingX2)
-    float                   ItemWidth;                      // Current item width for the column, preserved across rows
+    ImGuiTableColumnFlags   FlagsIn;                        // Flags as they were provided by user. See ImGuiTableColumnFlags_
+    ImGuiTableColumnFlags   Flags;                          // Effective flags. See ImGuiTableColumnFlags_
+    float                   MinX;                           // Absolute positions
+    float                   MaxX;
+    float                   InitStretchWeightOrWidth;       // Value passed to TableSetupColumn(). For Width it is a content width (_without padding_).
+    float                   StretchWeight;                  // Master width weight when (Flags & _WidthStretch). Often around ~1.0f initially.
+    float                   WidthAuto;                      // Automatic width
+    float                   WidthRequest;                   // Master width absolute value when !(Flags & _WidthStretch). When Stretch this is derived every frame from StretchWeight in TableUpdateLayout()
+    float                   WidthGiven;                     // Final/actual width visible == (MaxX - MinX), locked in TableUpdateLayout(). May be > WidthRequest to honor minimum width, may be < WidthRequest to honor shrinking columns down in tight space.
+    float                   WorkMinX;                       // Start position for the frame, currently ~(MinX + CellPaddingX)
+    float                   WorkMaxX;
+    float                   ItemWidth;
     float                   ContentMaxXFrozen;              // Contents maximum position for frozen rows (apart from headers), from which we can infer content width.
     float                   ContentMaxXUnfrozen;
     float                   ContentMaxXHeadersUsed;         // Contents maximum position for headers rows (regardless of freezing). TableHeader() automatically softclip itself + report ideal desired size, to avoid creating extraneous draw calls
@@ -1948,12 +2152,9 @@ struct ImGuiTableColumn
     bool                    IsSkipItems;                    // Do we want item submissions to this column to be completely ignored (no layout will happen).
     bool                    IsPreserveWidthAuto;
     ImS8                    NavLayerCurrent;                // ImGuiNavLayer in 1 byte
+    ImS8                    SortDirection;                  // ImGuiSortDirection_Ascending or ImGuiSortDirection_Descending
     ImU8                    AutoFitQueue;                   // Queue of 8 values for the next 8 frames to request auto-fit
     ImU8                    CannotSkipItemsQueue;           // Queue of 8 values for the next 8 frames to disable Clipped/SkipItem
-    ImU8                    SortDirection : 2;              // ImGuiSortDirection_Ascending or ImGuiSortDirection_Descending
-    ImU8                    SortDirectionsAvailCount : 2;   // Number of available sort directions (0 to 3)
-    ImU8                    SortDirectionsAvailMask : 4;    // Mask of available sort directions (1-bit each)
-    ImU8                    SortDirectionsAvailList;        // Ordered of available sort directions (2-bits each)
 
     ImGuiTableColumn()
     {
@@ -1976,7 +2177,7 @@ struct ImGuiTableCellData
     ImGuiTableColumnIdx         Column;     // Column number
 };
 
-// FIXME-TABLE: transient data could be stored in a per-stacked table structure: DrawSplitter, SortSpecs, incoming RowData
+// FIXME-TABLES: transient data could be stored in a per-stacked table structure: DrawSplitter, SortSpecs, incoming RowData
 struct ImGuiTable
 {
     ImGuiID                     ID;
@@ -2011,7 +2212,6 @@ struct ImGuiTable
     float                       BorderX1;
     float                       BorderX2;
     float                       HostIndentX;
-    float                       MinColumnWidth;
     float                       OuterPaddingX;
     float                       CellPaddingX;               // Padding from each borders
     float                       CellPaddingY;
@@ -2020,26 +2220,22 @@ struct ImGuiTable
     float                       LastOuterHeight;            // Outer height from last frame
     float                       LastFirstRowHeight;         // Height of first row from last frame
     float                       InnerWidth;                 // User value passed to BeginTable(), see comments at the top of BeginTable() for details.
-    float                       ColumnsGivenWidth;          // Sum of current column width
+    float                       ColumnsTotalWidth;          // Sum of current column width
     float                       ColumnsAutoFitWidth;        // Sum of ideal column width in order nothing to be clipped, used for auto-fitting and content width submission in outer window
     float                       ResizedColumnNextWidth;
-    float                       ResizeLockMinContentsX2;    // Lock minimum contents width while resizing down in order to not create feedback loops. But we allow growing the table.
     float                       RefScale;                   // Reference scale to be able to rescale columns on font/dpi changes.
-    ImRect                      OuterRect;                  // Note: for non-scrolling table, OuterRect.Max.y is often FLT_MAX until EndTable(), unless a height has been specified in BeginTable().
-    ImRect                      InnerRect;                  // InnerRect but without decoration. As with OuterRect, for non-scrolling tables, InnerRect.Max.y is
+    ImRect                      OuterRect;                  // Note: OuterRect.Max.y is often FLT_MAX until EndTable(), unless a height has been specified in BeginTable().
     ImRect                      WorkRect;
     ImRect                      InnerClipRect;
     ImRect                      BgClipRect;                 // We use this to cpu-clip cell background color fill
-    ImRect                      Bg0ClipRectForDrawCmd;      // Actual ImDrawCmd clip rect for BG0/1 channel. This tends to be == OuterWindow->ClipRect at BeginTable() because output in BG0/BG1 is cpu-clipped
-    ImRect                      Bg2ClipRectForDrawCmd;      // Actual ImDrawCmd clip rect for BG2 channel. This tends to be a correct, tight-fit, because output to BG2 are done by widgets relying on regular ClipRect.
+    ImRect                      BgClipRectForDrawCmd;
     ImRect                      HostClipRect;               // This is used to check if we can eventually merge our columns draw calls into the current draw call of the current window.
     ImRect                      HostBackupWorkRect;         // Backup of InnerWindow->WorkRect at the end of BeginTable()
     ImRect                      HostBackupParentWorkRect;   // Backup of InnerWindow->ParentWorkRect at the end of BeginTable()
-    ImRect                      HostBackupInnerClipRect;    // Backup of InnerWindow->ClipRect during PushTableBackground()/PopTableBackground()
+    ImRect                      HostBackupClipRect;         // Backup of InnerWindow->ClipRect during PushTableBackground()/PopTableBackground()
     ImVec2                      HostBackupPrevLineSize;     // Backup of InnerWindow->DC.PrevLineSize at the end of BeginTable()
     ImVec2                      HostBackupCurrLineSize;     // Backup of InnerWindow->DC.CurrLineSize at the end of BeginTable()
     ImVec2                      HostBackupCursorMaxPos;     // Backup of InnerWindow->DC.CursorMaxPos at the end of BeginTable()
-    ImVec2                      UserOuterSize;              // outer_size.x passed to BeginTable()
     ImVec1                      HostBackupColumnsOffset;    // Backup of OuterWindow->DC.ColumnsOffset at the end of BeginTable()
     float                       HostBackupItemWidth;        // Backup of OuterWindow->DC.ItemWidth at the end of BeginTable()
     int                         HostBackupItemWidthStackSize;// Backup of OuterWindow->DC.ItemWidthStack.Size at the end of BeginTable()
@@ -2056,15 +2252,14 @@ struct ImGuiTable
     ImGuiTableColumnIdx         DeclColumnsCount;           // Count calls to TableSetupColumn()
     ImGuiTableColumnIdx         HoveredColumnBody;          // Index of column whose visible region is being hovered. Important: == ColumnsCount when hovering empty region after the right-most column!
     ImGuiTableColumnIdx         HoveredColumnBorder;        // Index of column whose right-border is being hovered (for resizing).
-    ImGuiTableColumnIdx         AutoFitSingleColumn;        // Index of single column requesting auto-fit.
+    ImGuiTableColumnIdx         AutoFitSingleStretchColumn; // Index of single stretch column requesting auto-fit.
     ImGuiTableColumnIdx         ResizedColumn;              // Index of column being resized. Reset when InstanceCurrent==0.
     ImGuiTableColumnIdx         LastResizedColumn;          // Index of column being resized from previous frame.
     ImGuiTableColumnIdx         HeldHeaderColumn;           // Index of column header being held.
     ImGuiTableColumnIdx         ReorderColumn;              // Index of column being reordered. (not cleared)
     ImGuiTableColumnIdx         ReorderColumnDir;           // -1 or +1
-    ImGuiTableColumnIdx         LeftMostStretchedColumn;    // Index of left-most stretched column.
-    ImGuiTableColumnIdx         RightMostStretchedColumn;   // Index of right-most stretched column.
     ImGuiTableColumnIdx         RightMostEnabledColumn;     // Index of right-most non-hidden column.
+    ImGuiTableColumnIdx         LeftMostStretchedColumnDisplayOrder; // Display order of left-most stretched column.
     ImGuiTableColumnIdx         ContextPopupColumn;         // Column right-clicked on, of -1 if opening context menu from a neutral/empty spot
     ImGuiTableColumnIdx         FreezeRowsRequest;          // Requested frozen rows count
     ImGuiTableColumnIdx         FreezeRowsCount;            // Actual frozen row count (== FreezeRowsRequest, or == 0 when no scrolling offset)
@@ -2072,8 +2267,8 @@ struct ImGuiTable
     ImGuiTableColumnIdx         FreezeColumnsCount;         // Actual frozen columns count (== FreezeColumnsRequest, or == 0 when no scrolling offset)
     ImGuiTableColumnIdx         RowCellDataCurrent;         // Index of current RowCellData[] entry in current row
     ImGuiTableDrawChannelIdx    DummyDrawChannel;           // Redirect non-visible columns here.
-    ImGuiTableDrawChannelIdx    Bg2DrawChannelCurrent;      // For Selectable() and other widgets drawing accross columns after the freezing line. Index within DrawSplitter.Channels[]
-    ImGuiTableDrawChannelIdx    Bg2DrawChannelUnfrozen;
+    ImGuiTableDrawChannelIdx    Bg1DrawChannelCurrent;      // For Selectable() and other widgets drawing accross columns after the freezing line. Index within DrawSplitter.Channels[]
+    ImGuiTableDrawChannelIdx    Bg1DrawChannelUnfrozen;
     bool                        IsLayoutLocked;             // Set by TableUpdateLayout() which is called when beginning the first row.
     bool                        IsInsideRow;                // Set when inside TableBeginRow()/TableEndRow().
     bool                        IsInitializing;
@@ -2085,13 +2280,12 @@ struct ImGuiTable
     bool                        IsDefaultDisplayOrder;      // Set when display order is unchanged from default (DisplayOrder contains 0...Count-1)
     bool                        IsResetAllRequest;
     bool                        IsResetDisplayOrderRequest;
-    bool                        IsUnfrozenRows;             // Set when we got past the frozen row.
-    bool                        IsDefaultSizingPolicy;      // Set if user didn't explicitely set a sizing policy in BeginTable()
+    bool                        IsUnfrozen;                 // Set when we got past the frozen row.
     bool                        MemoryCompacted;
     bool                        HostSkipItems;              // Backup of InnerWindow->SkipItem at the end of BeginTable(), because we will overwrite InnerWindow->SkipItem on a per-column basis
 
-    IMGUI_API ImGuiTable()      { memset(this, 0, sizeof(*this)); LastFrameActive = -1; }
-    IMGUI_API ~ImGuiTable()     { IM_FREE(RawData); }
+    IMGUI_API ImGuiTable();
+    IMGUI_API ~ImGuiTable();
 };
 
 // sizeof() ~ 12
@@ -2151,7 +2345,7 @@ namespace ImGui
     IMGUI_API ImGuiWindow*  FindWindowByID(ImGuiID id);
     IMGUI_API ImGuiWindow*  FindWindowByName(const char* name);
     IMGUI_API void          UpdateWindowParentAndRootLinks(ImGuiWindow* window, ImGuiWindowFlags flags, ImGuiWindow* parent_window);
-    IMGUI_API ImVec2        CalcWindowNextAutoFitSize(ImGuiWindow* window);
+    IMGUI_API ImVec2        CalcWindowExpectedSize(ImGuiWindow* window);
     IMGUI_API bool          IsWindowChildOf(ImGuiWindow* window, ImGuiWindow* potential_parent);
     IMGUI_API bool          IsWindowAbove(ImGuiWindow* potential_above, ImGuiWindow* potential_below);
     IMGUI_API bool          IsWindowNavFocusable(ImGuiWindow* window);
@@ -2171,7 +2365,7 @@ namespace ImGui
     // Fonts, drawing
     IMGUI_API void          SetCurrentFont(ImFont* font);
     inline ImFont*          GetDefaultFont() { ImGuiContext& g = *GImGui; return g.IO.FontDefault ? g.IO.FontDefault : g.IO.Fonts->Fonts[0]; }
-    inline ImDrawList*      GetForegroundDrawList(ImGuiWindow* window) { IM_UNUSED(window); ImGuiContext& g = *GImGui; return &g.ForegroundDrawList; } // This seemingly unnecessary wrapper simplifies compatibility between the 'master' and 'docking' branches.
+    inline ImDrawList*      GetForegroundDrawList(ImGuiWindow* window) { return GetForegroundDrawList(window->Viewport); }
 
     // Init
     IMGUI_API void          Initialize(ImGuiContext* context);
@@ -2180,6 +2374,7 @@ namespace ImGui
     // NewFrame
     IMGUI_API void          UpdateHoveredWindowAndCaptureFlags();
     IMGUI_API void          StartMouseMovingWindow(ImGuiWindow* window);
+    IMGUI_API void          StartMouseMovingWindowOrNode(ImGuiWindow* window, ImGuiDockNode* node, bool undock_floating_node);
     IMGUI_API void          UpdateMouseMovingWindowNewFrame();
     IMGUI_API void          UpdateMouseMovingWindowEndFrame();
 
@@ -2187,6 +2382,11 @@ namespace ImGui
     IMGUI_API void          AddContextHook(ImGuiContext* context, const ImGuiContextHook* hook);
     IMGUI_API void          CallContextHooks(ImGuiContext* context, ImGuiContextHookType type);
 
+    // Viewports
+    IMGUI_API void         TranslateWindowsInViewport(ImGuiViewportP* viewport, const ImVec2& old_pos, const ImVec2& new_pos);
+    IMGUI_API void         ScaleWindowsInViewport(ImGuiViewportP* viewport, float scale);
+    IMGUI_API void         DestroyPlatformWindow(ImGuiViewportP* viewport);
+
     // Settings
     IMGUI_API void                  MarkIniSettingsDirty();
     IMGUI_API void                  MarkIniSettingsDirty(ImGuiWindow* window);
@@ -2249,7 +2449,7 @@ namespace ImGui
     IMGUI_API void          ClosePopupsOverWindow(ImGuiWindow* ref_window, bool restore_focus_to_window_under_popup);
     IMGUI_API bool          IsPopupOpen(ImGuiID id, ImGuiPopupFlags popup_flags);
     IMGUI_API bool          BeginPopupEx(ImGuiID id, ImGuiWindowFlags extra_flags);
-    IMGUI_API void          BeginTooltipEx(ImGuiWindowFlags extra_flags, ImGuiTooltipFlags tooltip_flags);
+    IMGUI_API bool          BeginTooltipEx(ImGuiWindowFlags extra_flags, ImGuiTooltipFlags tooltip_flags);
     IMGUI_API ImGuiWindow*  GetTopMostPopupModal();
     IMGUI_API ImVec2        FindBestWindowPosForPopup(ImGuiWindow* window);
     IMGUI_API ImVec2        FindBestWindowPosForPopupEx(const ImVec2& ref_pos, const ImVec2& size, ImGuiDir* last_dir, const ImRect& r_outer, const ImRect& r_avoid, ImGuiPopupPositionPolicy policy);
@@ -2277,7 +2477,6 @@ namespace ImGui
 
     // Inputs
     // FIXME: Eventually we should aim to move e.g. IsActiveIdUsingKey() into IsKeyXXX functions.
-    IMGUI_API void          SetItemUsingMouseWheel();
     inline bool             IsActiveIdUsingNavDir(ImGuiDir dir)                         { ImGuiContext& g = *GImGui; return (g.ActiveIdUsingNavDirMask & (1 << dir)) != 0; }
     inline bool             IsActiveIdUsingNavInput(ImGuiNavInput input)                { ImGuiContext& g = *GImGui; return (g.ActiveIdUsingNavInputMask & (1 << input)) != 0; }
     inline bool             IsActiveIdUsingKey(ImGuiKey key)                            { ImGuiContext& g = *GImGui; IM_ASSERT(key < 64); return (g.ActiveIdUsingKeyInputMask & ((ImU64)1 << key)) != 0; }
@@ -2287,6 +2486,54 @@ namespace ImGui
     inline bool             IsNavInputTest(ImGuiNavInput n, ImGuiInputReadMode rm)      { return (GetNavInputAmount(n, rm) > 0.0f); }
     IMGUI_API ImGuiKeyModFlags GetMergedKeyModFlags();
 
+    // Docking
+    // (some functions are only declared in imgui.cpp, see Docking section)
+    IMGUI_API void          DockContextInitialize(ImGuiContext* ctx);
+    IMGUI_API void          DockContextShutdown(ImGuiContext* ctx);
+    IMGUI_API void          DockContextClearNodes(ImGuiContext* ctx, ImGuiID root_id, bool clear_settings_refs); // Use root_id==0 to clear all
+    IMGUI_API void          DockContextRebuildNodes(ImGuiContext* ctx);
+    IMGUI_API void          DockContextUpdateUndocking(ImGuiContext* ctx);
+    IMGUI_API void          DockContextUpdateDocking(ImGuiContext* ctx);
+    IMGUI_API ImGuiID       DockContextGenNodeID(ImGuiContext* ctx);
+    IMGUI_API void          DockContextQueueDock(ImGuiContext* ctx, ImGuiWindow* target, ImGuiDockNode* target_node, ImGuiWindow* payload, ImGuiDir split_dir, float split_ratio, bool split_outer);
+    IMGUI_API void          DockContextQueueUndockWindow(ImGuiContext* ctx, ImGuiWindow* window);
+    IMGUI_API void          DockContextQueueUndockNode(ImGuiContext* ctx, ImGuiDockNode* node);
+    IMGUI_API bool          DockContextCalcDropPosForDocking(ImGuiWindow* target, ImGuiDockNode* target_node, ImGuiWindow* payload, ImGuiDir split_dir, bool split_outer, ImVec2* out_pos);
+    IMGUI_API bool          DockNodeBeginAmendTabBar(ImGuiDockNode* node);
+    IMGUI_API void          DockNodeEndAmendTabBar();
+    inline ImGuiDockNode*   DockNodeGetRootNode(ImGuiDockNode* node)    { while (node->ParentNode) node = node->ParentNode; return node; }
+    inline int              DockNodeGetDepth(const ImGuiDockNode* node) { int depth = 0; while (node->ParentNode) { node = node->ParentNode; depth++; } return depth; }
+    inline ImGuiDockNode*   GetWindowDockNode()                         { ImGuiContext& g = *GImGui; return g.CurrentWindow->DockNode; }
+    IMGUI_API bool          GetWindowAlwaysWantOwnTabBar(ImGuiWindow* window);
+    IMGUI_API void          BeginDocked(ImGuiWindow* window, bool* p_open);
+    IMGUI_API void          BeginDockableDragDropSource(ImGuiWindow* window);
+    IMGUI_API void          BeginDockableDragDropTarget(ImGuiWindow* window);
+    IMGUI_API void          SetWindowDock(ImGuiWindow* window, ImGuiID dock_id, ImGuiCond cond);
+
+    // Docking - Builder function needs to be generally called before the node is used/submitted.
+    // - The DockBuilderXXX functions are designed to _eventually_ become a public API, but it is too early to expose it and guarantee stability.
+    // - Do not hold on ImGuiDockNode* pointers! They may be invalidated by any split/merge/remove operation and every frame.
+    // - To create a DockSpace() node, make sure to set the ImGuiDockNodeFlags_DockSpace flag when calling DockBuilderAddNode().
+    //   You can create dockspace nodes (attached to a window) _or_ floating nodes (carry its own window) with this API.
+    // - DockBuilderSplitNode() create 2 child nodes within 1 node. The initial node becomes a parent node.
+    // - If you intend to split the node immediately after creation using DockBuilderSplitNode(), make sure
+    //   to call DockBuilderSetNodeSize() beforehand. If you don't, the resulting split sizes may not be reliable.
+    // - Call DockBuilderFinish() after you are done.
+    IMGUI_API void          DockBuilderDockWindow(const char* window_name, ImGuiID node_id);
+    IMGUI_API ImGuiDockNode*DockBuilderGetNode(ImGuiID node_id);
+    inline ImGuiDockNode*   DockBuilderGetCentralNode(ImGuiID node_id)              { ImGuiDockNode* node = DockBuilderGetNode(node_id); if (!node) return NULL; return DockNodeGetRootNode(node)->CentralNode; }
+    IMGUI_API ImGuiID       DockBuilderAddNode(ImGuiID node_id = 0, ImGuiDockNodeFlags flags = 0);
+    IMGUI_API void          DockBuilderRemoveNode(ImGuiID node_id);                 // Remove node and all its child, undock all windows
+    IMGUI_API void          DockBuilderRemoveNodeDockedWindows(ImGuiID node_id, bool clear_settings_refs = true);
+    IMGUI_API void          DockBuilderRemoveNodeChildNodes(ImGuiID node_id);       // Remove all split/hierarchy. All remaining docked windows will be re-docked to the remaining root node (node_id).
+    IMGUI_API void          DockBuilderSetNodePos(ImGuiID node_id, ImVec2 pos);
+    IMGUI_API void          DockBuilderSetNodeSize(ImGuiID node_id, ImVec2 size);
+    IMGUI_API ImGuiID       DockBuilderSplitNode(ImGuiID node_id, ImGuiDir split_dir, float size_ratio_for_node_at_dir, ImGuiID* out_id_at_dir, ImGuiID* out_id_at_opposite_dir); // Create 2 child nodes in this parent node.
+    IMGUI_API void          DockBuilderCopyDockSpace(ImGuiID src_dockspace_id, ImGuiID dst_dockspace_id, ImVector<const char*>* in_window_remap_pairs);
+    IMGUI_API void          DockBuilderCopyNode(ImGuiID src_node_id, ImGuiID dst_node_id, ImVector<ImGuiID>* out_node_remap_pairs);
+    IMGUI_API void          DockBuilderCopyWindowSettings(const char* src_name, const char* dst_name);
+    IMGUI_API void          DockBuilderFinish(ImGuiID node_id);
+
     // Drag and Drop
     IMGUI_API bool          BeginDragDropTargetCustom(const ImRect& bb, ImGuiID id);
     IMGUI_API void          ClearDragDrop();
@@ -2307,6 +2554,7 @@ namespace ImGui
     // Tables: Candidates for public API
     IMGUI_API void          TableOpenContextMenu(int column_n = -1);
     IMGUI_API void          TableSetColumnWidth(int column_n, float width);
+    IMGUI_API void          TableSetColumnIsEnabled(int column_n, bool enabled);
     IMGUI_API void          TableSetColumnSortDirection(int column_n, ImGuiSortDirection sort_direction, bool append_to_sort_specs);
     IMGUI_API int           TableGetHoveredColumn(); // May use (TableGetColumnFlags() & ImGuiTableColumnFlags_IsHovered) instead. Return hovered column. return -1 when table is not hovered. return columns_count if the unused space at the right of visible columns is hovered.
     IMGUI_API float         TableGetHeaderRowHeight();
@@ -2321,15 +2569,12 @@ namespace ImGui
     IMGUI_API void          TableSetupDrawChannels(ImGuiTable* table);
     IMGUI_API void          TableUpdateLayout(ImGuiTable* table);
     IMGUI_API void          TableUpdateBorders(ImGuiTable* table);
-    IMGUI_API void          TableUpdateColumnsWeightFromWidth(ImGuiTable* table);
     IMGUI_API void          TableDrawBorders(ImGuiTable* table);
     IMGUI_API void          TableDrawContextMenu(ImGuiTable* table);
     IMGUI_API void          TableMergeDrawChannels(ImGuiTable* table);
     IMGUI_API void          TableSortSpecsSanitize(ImGuiTable* table);
     IMGUI_API void          TableSortSpecsBuild(ImGuiTable* table);
-    IMGUI_API ImGuiSortDirection TableGetColumnNextSortDirection(ImGuiTableColumn* column);
-    IMGUI_API void          TableFixColumnSortDirection(ImGuiTable* table, ImGuiTableColumn* column);
-    IMGUI_API float         TableGetColumnWidthAuto(ImGuiTable* table, ImGuiTableColumn* column);
+    IMGUI_API void          TableFixColumnSortDirection(ImGuiTableColumn* column);
     IMGUI_API void          TableBeginRow(ImGuiTable* table);
     IMGUI_API void          TableEndRow(ImGuiTable* table);
     IMGUI_API void          TableBeginCell(ImGuiTable* table, int column_n);
@@ -2337,7 +2582,6 @@ namespace ImGui
     IMGUI_API ImRect        TableGetCellBgRect(const ImGuiTable* table, int column_n);
     IMGUI_API const char*   TableGetColumnName(const ImGuiTable* table, int column_n);
     IMGUI_API ImGuiID       TableGetColumnResizeID(const ImGuiTable* table, int column_n, int instance_no = 0);
-    IMGUI_API float         TableGetMaxColumnWidth(const ImGuiTable* table, int column_n);
     IMGUI_API void          TableSetColumnWidthAutoSingle(ImGuiTable* table, int column_n);
     IMGUI_API void          TableSetColumnWidthAutoAll(ImGuiTable* table);
     IMGUI_API void          TableRemove(ImGuiTable* table);
@@ -2354,13 +2598,15 @@ namespace ImGui
     IMGUI_API ImGuiTableSettings*   TableSettingsFindByID(ImGuiID id);
 
     // Tab Bars
-    IMGUI_API bool          BeginTabBarEx(ImGuiTabBar* tab_bar, const ImRect& bb, ImGuiTabBarFlags flags);
+    IMGUI_API bool          BeginTabBarEx(ImGuiTabBar* tab_bar, const ImRect& bb, ImGuiTabBarFlags flags, ImGuiDockNode* dock_node);
     IMGUI_API ImGuiTabItem* TabBarFindTabByID(ImGuiTabBar* tab_bar, ImGuiID tab_id);
+    IMGUI_API ImGuiTabItem* TabBarFindMostRecentlySelectedTabForActiveWindow(ImGuiTabBar* tab_bar);
+    IMGUI_API void          TabBarAddTab(ImGuiTabBar* tab_bar, ImGuiTabItemFlags tab_flags, ImGuiWindow* window);
     IMGUI_API void          TabBarRemoveTab(ImGuiTabBar* tab_bar, ImGuiID tab_id);
     IMGUI_API void          TabBarCloseTab(ImGuiTabBar* tab_bar, ImGuiTabItem* tab);
     IMGUI_API void          TabBarQueueReorder(ImGuiTabBar* tab_bar, const ImGuiTabItem* tab, int dir);
     IMGUI_API bool          TabBarProcessReorder(ImGuiTabBar* tab_bar);
-    IMGUI_API bool          TabItemEx(ImGuiTabBar* tab_bar, const char* label, bool* p_open, ImGuiTabItemFlags flags);
+    IMGUI_API bool          TabItemEx(ImGuiTabBar* tab_bar, const char* label, bool* p_open, ImGuiTabItemFlags flags, ImGuiWindow* docked_window);
     IMGUI_API ImVec2        TabItemCalcSize(const char* label, bool has_close_button);
     IMGUI_API void          TabItemBackground(ImDrawList* draw_list, const ImRect& bb, ImGuiTabItemFlags flags, ImU32 col);
     IMGUI_API void          TabItemLabelAndCloseButton(ImDrawList* draw_list, const ImRect& bb, ImGuiTabItemFlags flags, ImVec2 frame_padding, const char* label, ImGuiID tab_id, ImGuiID close_button_id, bool is_contents_visible, bool* out_just_closed, bool* out_text_clipped);
@@ -2386,6 +2632,7 @@ namespace ImGui
     IMGUI_API void          RenderCheckMark(ImDrawList* draw_list, ImVec2 pos, ImU32 col, float sz);
     IMGUI_API void          RenderMouseCursor(ImDrawList* draw_list, ImVec2 pos, float scale, ImGuiMouseCursor mouse_cursor, ImU32 col_fill, ImU32 col_border, ImU32 col_shadow);
     IMGUI_API void          RenderArrowPointingAt(ImDrawList* draw_list, ImVec2 pos, ImVec2 half_sz, ImGuiDir direction, ImU32 col);
+    IMGUI_API void          RenderArrowDockMenu(ImDrawList* draw_list, ImVec2 p_min, float sz, ImU32 col);
     IMGUI_API void          RenderRectFilledRangeH(ImDrawList* draw_list, const ImRect& rect, ImU32 col, float x_start_norm, float x_end_norm, float rounding);
     IMGUI_API void          RenderRectFilledWithHole(ImDrawList* draw_list, ImRect outer, ImRect inner, ImU32 col, float rounding);
 
@@ -2399,7 +2646,7 @@ namespace ImGui
     IMGUI_API void          TextEx(const char* text, const char* text_end = NULL, ImGuiTextFlags flags = 0);
     IMGUI_API bool          ButtonEx(const char* label, const ImVec2& size_arg = ImVec2(0, 0), ImGuiButtonFlags flags = 0);
     IMGUI_API bool          CloseButton(ImGuiID id, const ImVec2& pos);
-    IMGUI_API bool          CollapseButton(ImGuiID id, const ImVec2& pos);
+    IMGUI_API bool          CollapseButton(ImGuiID id, const ImVec2& pos, ImGuiDockNode* dock_node);
     IMGUI_API bool          ArrowButtonEx(const char* str_id, ImGuiDir dir, ImVec2 size_arg, ImGuiButtonFlags flags = 0);
     IMGUI_API void          Scrollbar(ImGuiAxis axis);
     IMGUI_API bool          ScrollbarEx(const ImRect& bb, ImGuiID id, ImGuiAxis axis, float* p_scroll_v, float avail_v, float contents_v, ImDrawCornerFlags rounding_corners);
@@ -2408,8 +2655,6 @@ namespace ImGui
     IMGUI_API ImGuiID       GetWindowScrollbarID(ImGuiWindow* window, ImGuiAxis axis);
     IMGUI_API ImGuiID       GetWindowResizeID(ImGuiWindow* window, int n); // 0..3: corners, 4..7: borders
     IMGUI_API void          SeparatorEx(ImGuiSeparatorFlags flags);
-    IMGUI_API bool          CheckboxFlags(const char* label, ImS64* flags, ImS64 flags_value);
-    IMGUI_API bool          CheckboxFlags(const char* label, ImU64* flags, ImU64 flags_value);
 
     // Widgets low-level behaviors
     IMGUI_API bool          ButtonBehavior(const ImRect& bb, ImGuiID id, bool* out_hovered, bool* out_held, ImGuiButtonFlags flags = 0);
@@ -2468,8 +2713,9 @@ namespace ImGui
     inline void             DebugStartItemPicker()                                  { ImGuiContext& g = *GImGui; g.DebugItemPickerActive = true; }
 
     IMGUI_API void          DebugNodeColumns(ImGuiOldColumns* columns);
-    IMGUI_API void          DebugNodeDrawList(ImGuiWindow* window, const ImDrawList* draw_list, const char* label);
-    IMGUI_API void          DebugNodeDrawCmdShowMeshAndBoundingBox(ImGuiWindow* window, const ImDrawList* draw_list, const ImDrawCmd* draw_cmd, bool show_mesh, bool show_aabb);
+    IMGUI_API void          DebugNodeDockNode(ImGuiDockNode* node, const char* label);
+    IMGUI_API void          DebugNodeDrawList(ImGuiWindow* window, ImGuiViewportP* viewport, const ImDrawList* draw_list, const char* label);
+    IMGUI_API void          DebugNodeDrawCmdShowMeshAndBoundingBox(ImDrawList* out_draw_list, const ImDrawList* draw_list, const ImDrawCmd* draw_cmd, bool show_mesh, bool show_aabb);
     IMGUI_API void          DebugNodeStorage(ImGuiStorage* storage, const char* label);
     IMGUI_API void          DebugNodeTabBar(ImGuiTabBar* tab_bar, const char* label);
     IMGUI_API void          DebugNodeTable(ImGuiTable* table);
@@ -2477,6 +2723,7 @@ namespace ImGui
     IMGUI_API void          DebugNodeWindow(ImGuiWindow* window, const char* label);
     IMGUI_API void          DebugNodeWindowSettings(ImGuiWindowSettings* settings);
     IMGUI_API void          DebugNodeWindowsList(ImVector<ImGuiWindow*>* windows, const char* label);
+    IMGUI_API void          DebugNodeViewport(ImGuiViewportP* viewport);
 
 } // namespace ImGui
 

imgui_widgets.cpp

@@ -1,4 +1,4 @@
-// dear imgui, v1.80
+// dear imgui, v1.80 WIP
 // (widgets code)
 
 /*
@@ -86,10 +86,6 @@ Index of this file:
 // Data
 //-------------------------------------------------------------------------
 
-// Widgets
-static const float          DRAGDROP_HOLD_TO_OPEN_TIMER = 0.70f;    // Time for drag-hold to activate items accepting the ImGuiButtonFlags_PressedOnDragDropHold button behavior.
-static const float          DRAG_MOUSE_THRESHOLD_FACTOR = 0.50f;    // Multiplier for the default value of io.MouseDragThreshold to make DragFloat/DragInt react faster to mouse drags.
-
 // Those MIN/MAX values are not define because we need to point to them
 static const signed char    IM_S8_MIN  = -128;
 static const signed char    IM_S8_MAX  = 127;
@@ -500,7 +496,7 @@ bool ImGui::ButtonBehavior(const ImRect& bb, ImGuiID id, bool* out_hovered, bool
         flags |= ImGuiButtonFlags_PressedOnDefault_;
 
     ImGuiWindow* backup_hovered_window = g.HoveredWindow;
-    const bool flatten_hovered_children = (flags & ImGuiButtonFlags_FlattenChildren) && g.HoveredRootWindow == window;
+    const bool flatten_hovered_children = (flags & ImGuiButtonFlags_FlattenChildren) && g.HoveredRootWindow == window->RootWindow;
     if (flatten_hovered_children)
         g.HoveredWindow = window;
 
@@ -520,9 +516,10 @@ bool ImGui::ButtonBehavior(const ImRect& bb, ImGuiID id, bool* out_hovered, bool
     if (g.DragDropActive && (flags & ImGuiButtonFlags_PressedOnDragDropHold) && !(g.DragDropSourceFlags & ImGuiDragDropFlags_SourceNoHoldToOpenOthers))
         if (IsItemHovered(ImGuiHoveredFlags_AllowWhenBlockedByActiveItem))
         {
+            const float DRAG_DROP_HOLD_TIMER = 0.70f;
             hovered = true;
             SetHoveredID(id);
-            if (CalcTypematicRepeatAmount(g.HoveredIdTimer + 0.0001f - g.IO.DeltaTime, g.HoveredIdTimer + 0.0001f, DRAGDROP_HOLD_TO_OPEN_TIMER, 0.00f))
+            if (CalcTypematicRepeatAmount(g.HoveredIdTimer + 0.0001f - g.IO.DeltaTime, g.HoveredIdTimer + 0.0001f, DRAG_DROP_HOLD_TIMER, 0.00f))
             {
                 pressed = true;
                 g.DragDropHoldJustPressedId = id;
@@ -809,7 +806,8 @@ bool ImGui::CloseButton(ImGuiID id, const ImVec2& pos)//, float size)
     return pressed;
 }
 
-bool ImGui::CollapseButton(ImGuiID id, const ImVec2& pos)
+// The Collapse button also functions as a Dock Menu button.
+bool ImGui::CollapseButton(ImGuiID id, const ImVec2& pos, ImGuiDockNode* dock_node)
 {
     ImGuiContext& g = *GImGui;
     ImGuiWindow* window = g.CurrentWindow;
@@ -820,16 +818,22 @@ bool ImGui::CollapseButton(ImGuiID id, const ImVec2& pos)
     bool pressed = ButtonBehavior(bb, id, &hovered, &held, ImGuiButtonFlags_None);
 
     // Render
+    //bool is_dock_menu = (window->DockNodeAsHost && !window->Collapsed);
+    ImVec2 off = dock_node ? ImVec2(IM_FLOOR(-g.Style.ItemInnerSpacing.x * 0.5f) + 0.5f, 0.0f) : ImVec2(0.0f, 0.0f);
     ImU32 bg_col = GetColorU32((held && hovered) ? ImGuiCol_ButtonActive : hovered ? ImGuiCol_ButtonHovered : ImGuiCol_Button);
     ImU32 text_col = GetColorU32(ImGuiCol_Text);
     ImVec2 center = bb.GetCenter();
     if (hovered || held)
-        window->DrawList->AddCircleFilled(center/*+ ImVec2(0.0f, -0.5f)*/, g.FontSize * 0.5f + 1.0f, bg_col, 12);
+        window->DrawList->AddCircleFilled(center + off + ImVec2(0,-0.5f), g.FontSize * 0.5f + 1.0f, bg_col, 12);
+
+    if (dock_node)
+        RenderArrowDockMenu(window->DrawList, bb.Min + g.Style.FramePadding, g.FontSize, text_col);
+    else
         RenderArrow(window->DrawList, bb.Min + g.Style.FramePadding, text_col, window->Collapsed ? ImGuiDir_Right : ImGuiDir_Down, 1.0f);
 
     // Switch to moving the window after mouse is moved beyond the initial drag threshold
     if (IsItemActive() && IsMouseDragging(0))
-        StartMouseMovingWindow(window);
+        StartMouseMovingWindowOrNode(window, dock_node, true);
 
     return pressed;
 }
@@ -1066,10 +1070,7 @@ bool ImGui::Checkbox(const char* label, bool* v)
     const ImRect total_bb(pos, pos + ImVec2(square_sz + (label_size.x > 0.0f ? style.ItemInnerSpacing.x + label_size.x : 0.0f), label_size.y + style.FramePadding.y * 2.0f));
     ItemSize(total_bb, style.FramePadding.y);
     if (!ItemAdd(total_bb, id))
-    {
-        IMGUI_TEST_ENGINE_ITEM_INFO(id, label, window->DC.ItemFlags | ImGuiItemStatusFlags_Checkable | (*v ? ImGuiItemStatusFlags_Checked : 0));
         return false;
-    }
 
     bool hovered, held;
     bool pressed = ButtonBehavior(total_bb, id, &hovered, &held);
@@ -1145,16 +1146,6 @@ bool ImGui::CheckboxFlags(const char* label, unsigned int* flags, unsigned int f
     return CheckboxFlagsT(label, flags, flags_value);
 }
 
-bool ImGui::CheckboxFlags(const char* label, ImS64* flags, ImS64 flags_value)
-{
-    return CheckboxFlagsT(label, flags, flags_value);
-}
-
-bool ImGui::CheckboxFlags(const char* label, ImU64* flags, ImU64 flags_value)
-{
-    return CheckboxFlagsT(label, flags, flags_value);
-}
-
 bool ImGui::RadioButton(const char* label, bool active)
 {
     ImGuiWindow* window = GetCurrentWindow();
@@ -1617,7 +1608,7 @@ bool ImGui::BeginCombo(const char* label, const char* preview_value, ImGuiComboF
         if (popup_window->WasActive)
         {
             // Always override 'AutoPosLastDirection' to not leave a chance for a past value to affect us.
-            ImVec2 size_expected = CalcWindowNextAutoFitSize(popup_window);
+            ImVec2 size_expected = CalcWindowExpectedSize(popup_window);
             if (flags & ImGuiComboFlags_PopupAlignLeft)
                 popup_window->AutoPosLastDirection = ImGuiDir_Left; // "Below, Toward Left"
             else
@@ -1636,7 +1627,6 @@ bool ImGui::BeginCombo(const char* label, const char* preview_value, ImGuiComboF
     PopStyleVar();
     if (!ret)
     {
-        EndPopup();
         IM_ASSERT(0);   // This should never happen as we tested for IsPopupOpen() above
         return false;
     }
@@ -1716,9 +1706,6 @@ bool ImGui::Combo(const char* label, int* current_item, bool (*items_getter)(voi
     }
 
     EndCombo();
-    if (value_changed)
-        MarkItemEdited(g.CurrentWindow->DC.LastItemId);
-
     return value_changed;
 }
 
@@ -2111,7 +2098,7 @@ bool ImGui::DragBehaviorT(ImGuiDataType data_type, TYPE* v, float v_speed, const
 
     // Inputs accumulates into g.DragCurrentAccum, which is flushed into the current value as soon as it makes a difference with our precision settings
     float adjust_delta = 0.0f;
-    if (g.ActiveIdSource == ImGuiInputSource_Mouse && IsMousePosValid() && IsMouseDragPastThreshold(0, g.IO.MouseDragThreshold * DRAG_MOUSE_THRESHOLD_FACTOR))
+    if (g.ActiveIdSource == ImGuiInputSource_Mouse && IsMousePosValid() && g.IO.MouseDragMaxDistanceSqr[0] > 1.0f * 1.0f)
     {
         adjust_delta = g.IO.MouseDelta[axis];
         if (g.IO.KeyAlt)
@@ -2274,7 +2261,7 @@ bool ImGui::DragScalar(const char* label, ImGuiDataType data_type, void* p_data,
     else if (data_type == ImGuiDataType_S32 && strcmp(format, "%d") != 0) // (FIXME-LEGACY: Patch old "%.0f" format string to use "%d", read function more details.)
         format = PatchFormatStringFloatToInt(format);
 
-    // Tabbing or CTRL-clicking on Drag turns it into an InputText
+    // Tabbing or CTRL-clicking on Drag turns it into an input box
     const bool hovered = ItemHoverable(frame_bb, id);
     const bool temp_input_allowed = (flags & ImGuiSliderFlags_NoInput) == 0;
     bool temp_input_is_active = temp_input_allowed && TempInputIsActive(id);
@@ -2295,15 +2282,6 @@ bool ImGui::DragScalar(const char* label, ImGuiDataType data_type, void* p_data,
                 FocusableItemUnregister(window);
             }
         }
-        // Experimental: simple click (without moving) turns Drag into an InputText
-        // FIXME: Currently polling ImGuiConfigFlags_IsTouchScreen, may either poll an hypothetical ImGuiBackendFlags_HasKeyboard and/or an explicit drag settings.
-        if (g.IO.ConfigDragClickToInputText && temp_input_allowed && !temp_input_is_active)
-            if (g.ActiveId == id && hovered && g.IO.MouseReleased[0] && !IsMouseDragPastThreshold(0, g.IO.MouseDragThreshold * DRAG_MOUSE_THRESHOLD_FACTOR))
-            {
-                g.NavInputId = id;
-                temp_input_is_active = true;
-                FocusableItemUnregister(window);
-            }
     }
 
     if (temp_input_is_active)
@@ -3859,7 +3837,6 @@ bool ImGui::InputTextEx(const char* label, const char* hint, char* buf, int buf_
         PopStyleColor();
         if (!child_visible)
         {
-            EndChild();
             EndGroup();
             return false;
         }
@@ -4557,7 +4534,10 @@ bool ImGui::InputTextEx(const char* label, const char* hint, char* buf, int buf_
 
             // Notify OS of text input position for advanced IME (-1 x offset so that Windows IME can cover our cursor. Bit of an extra nicety.)
             if (!is_readonly)
-                g.PlatformImePos = ImVec2(cursor_screen_pos.x - 1.0f, cursor_screen_pos.y - g.FontSize);
+            {
+                g.PlatformImePos = ImVec2(cursor_screen_pos.x - 1, cursor_screen_pos.y - g.FontSize);
+                g.PlatformImePosViewport = window->Viewport;
+            }
         }
     }
     else
@@ -5373,7 +5353,8 @@ void ImGui::ColorTooltip(const char* text, const float* col, ImGuiColorEditFlags
 {
     ImGuiContext& g = *GImGui;
 
-    BeginTooltipEx(0, ImGuiTooltipFlags_OverridePreviousTooltip);
+    if (!BeginTooltipEx(0, ImGuiTooltipFlags_OverridePreviousTooltip))
+        return;
     const char* text_end = text ? FindRenderedTextEnd(text, NULL) : text;
     if (text_end > text)
     {
@@ -5910,25 +5891,21 @@ bool ImGui::CollapsingHeader(const char* label, ImGuiTreeNodeFlags flags)
     return TreeNodeBehavior(window->GetID(label), flags | ImGuiTreeNodeFlags_CollapsingHeader, label);
 }
 
-// p_visible == NULL                        : regular collapsing header
-// p_visible != NULL && *p_visible == true  : show a small close button on the corner of the header, clicking the button will set *p_visible = false
-// p_visible != NULL && *p_visible == false : do not show the header at all
-// Do not mistake this with the Open state of the header itself, which you can adjust with SetNextItemOpen() or ImGuiTreeNodeFlags_DefaultOpen.
-bool ImGui::CollapsingHeader(const char* label, bool* p_visible, ImGuiTreeNodeFlags flags)
+bool ImGui::CollapsingHeader(const char* label, bool* p_open, ImGuiTreeNodeFlags flags)
 {
     ImGuiWindow* window = GetCurrentWindow();
     if (window->SkipItems)
         return false;
 
-    if (p_visible && !*p_visible)
+    if (p_open && !*p_open)
         return false;
 
     ImGuiID id = window->GetID(label);
     flags |= ImGuiTreeNodeFlags_CollapsingHeader;
-    if (p_visible)
+    if (p_open)
         flags |= ImGuiTreeNodeFlags_AllowItemOverlap | ImGuiTreeNodeFlags_ClipLabelForTrailingButton;
     bool is_open = TreeNodeBehavior(id, flags, label);
-    if (p_visible != NULL)
+    if (p_open != NULL)
     {
         // Create a small overlapping close button
         // FIXME: We can evolve this into user accessible helpers to add extra buttons on title bars, headers, etc.
@@ -5940,7 +5917,7 @@ bool ImGui::CollapsingHeader(const char* label, bool* p_visible, ImGuiTreeNodeFl
         float button_y = window->DC.LastItemRect.Min.y;
         ImGuiID close_button_id = GetIDWithSeed("#CLOSE", NULL, id);
         if (CloseButton(close_button_id, ImVec2(button_x, button_y)))
-            *p_visible = false;
+            *p_open = false;
         last_item_backup.Restore();
     }
 
@@ -6155,8 +6132,11 @@ bool ImGui::ListBoxHeader(const char* label, const ImVec2& size_arg)
     if (label_size.x > 0)
         RenderText(ImVec2(frame_bb.Max.x + style.ItemInnerSpacing.x, frame_bb.Min.y + style.FramePadding.y), label);
 
-    BeginChildFrame(id, frame_bb.GetSize());
-    return true;
+    // FIXME-NEWBEGIN: Use to be return true so we'll trigger more issues.
+    bool ret = BeginChildFrame(id, frame_bb.GetSize());
+    if (!ret)
+        EndGroup();
+    return ret;
 }
 
 // FIXME: In principle this function should be called EndListBox(). We should rename it after re-evaluating if we want to keep the same signature.
@@ -6181,9 +6161,7 @@ bool ImGui::ListBoxHeader(const char* label, int items_count, int height_in_item
 // FIXME: In principle this function should be called EndListBox(). We should rename it after re-evaluating if we want to keep the same signature.
 void ImGui::ListBoxFooter()
 {
-    ImGuiWindow * window = GetCurrentWindow();
-    IM_ASSERT((window->Flags & ImGuiWindowFlags_ChildWindow) && "Mismatched ListBoxHeader/ListBoxFooter calls. Did you test the return value of ListBoxHeader()?");
-    ImGuiWindow* parent_window = window->ParentWindow;
+    ImGuiWindow* parent_window = GetCurrentWindow()->ParentWindow;
     const ImRect bb = parent_window->DC.LastItemRect;
     const ImGuiStyle& style = GetStyle();
 
@@ -6245,11 +6223,6 @@ bool ImGui::ListBox(const char* label, int* current_item, bool (*items_getter)(v
 // - PlotLines()
 // - PlotHistogram()
 //-------------------------------------------------------------------------
-// Plot/Graph widgets are not very good.
-// Consider writing your own, or using a third-party one, see:
-// - ImPlot https://github.com/epezent/implot
-// - others https://github.com/ocornut/imgui/wiki/Useful-Widgets
-//-------------------------------------------------------------------------
 
 int ImGui::PlotEx(ImGuiPlotType plot_type, const char* label, float (*values_getter)(void* data, int idx), void* data, int values_count, int values_offset, const char* overlay_text, float scale_min, float scale_max, ImVec2 frame_size)
 {
@@ -6562,24 +6535,42 @@ void ImGui::EndMenuBar()
     window->DC.MenuBarAppending = false;
 }
 
-// For the main menu bar, which cannot be moved, we honor g.Style.DisplaySafeAreaPadding to ensure text can be visible on a TV set.
 bool ImGui::BeginMainMenuBar()
 {
     ImGuiContext& g = *GImGui;
+    ImGuiViewportP* viewport = g.Viewports[0];
+    ImGuiWindow* menu_bar_window = FindWindowByName("##MainMenuBar");
+
+    // For the main menu bar, which cannot be moved, we honor g.Style.DisplaySafeAreaPadding to ensure text can be visible on a TV set.
     g.NextWindowData.MenuBarOffsetMinVal = ImVec2(g.Style.DisplaySafeAreaPadding.x, ImMax(g.Style.DisplaySafeAreaPadding.y - g.Style.FramePadding.y, 0.0f));
-    SetNextWindowPos(ImVec2(0.0f, 0.0f));
-    SetNextWindowSize(ImVec2(g.IO.DisplaySize.x, g.NextWindowData.MenuBarOffsetMinVal.y + g.FontBaseSize + g.Style.FramePadding.y));
+
+    // Get our rectangle at the top of the work area
+    if (menu_bar_window == NULL || menu_bar_window->BeginCount == 0)
+    {
+        // Set window position
+        // We don't attempt to calculate our height ahead, as it depends on the per-viewport font size. However menu-bar will affect the minimum window size so we'll get the right height.
+        ImVec2 menu_bar_pos = viewport->Pos + viewport->CurrWorkOffsetMin;
+        ImVec2 menu_bar_size = ImVec2(viewport->Size.x - viewport->CurrWorkOffsetMin.x + viewport->CurrWorkOffsetMax.x, 1.0f);
+        SetNextWindowPos(menu_bar_pos);
+        SetNextWindowSize(menu_bar_size);
+    }
+
+    // Create window
+    SetNextWindowViewport(viewport->ID); // Enforce viewport so we don't create our own viewport when ImGuiConfigFlags_ViewportsNoMerge is set.
     PushStyleVar(ImGuiStyleVar_WindowRounding, 0.0f);
-    PushStyleVar(ImGuiStyleVar_WindowMinSize, ImVec2(0, 0));
-    ImGuiWindowFlags window_flags = ImGuiWindowFlags_NoTitleBar | ImGuiWindowFlags_NoResize | ImGuiWindowFlags_NoMove | ImGuiWindowFlags_NoScrollbar | ImGuiWindowFlags_NoSavedSettings | ImGuiWindowFlags_MenuBar;
+    PushStyleVar(ImGuiStyleVar_WindowMinSize, ImVec2(0, 0));    // Lift normal size constraint, however the presence of a menu-bar will give us the minimum height we want.
+    ImGuiWindowFlags window_flags = ImGuiWindowFlags_NoDocking | ImGuiWindowFlags_NoTitleBar | ImGuiWindowFlags_NoResize | ImGuiWindowFlags_NoMove | ImGuiWindowFlags_NoScrollbar | ImGuiWindowFlags_NoSavedSettings | ImGuiWindowFlags_MenuBar;
     bool is_open = Begin("##MainMenuBar", NULL, window_flags) && BeginMenuBar();
     PopStyleVar(2);
+
+    // Report our size into work area (for next frame) using actual window size
+    menu_bar_window = GetCurrentWindow();
+    if (menu_bar_window->BeginCount == 1)
+        viewport->CurrWorkOffsetMin.y += menu_bar_window->Size.y;
+
     g.NextWindowData.MenuBarOffsetMinVal = ImVec2(0.0f, 0.0f);
     if (!is_open)
-    {
-        End();
         return false;
-    }
     return true; //-V1020
 }
 
@@ -6846,6 +6837,7 @@ bool ImGui::MenuItem(const char* label, const char* shortcut, bool* p_selected,
 // - TabBarCalcTabID() [Internal]
 // - TabBarCalcMaxTabWidth() [Internal]
 // - TabBarFindTabById() [Internal]
+// - TabBarAddTab() [Internal]
 // - TabBarRemoveTab() [Internal]
 // - TabBarCloseTab() [Internal]
 // - TabBarScrollClamp() [Internal]
@@ -6867,7 +6859,7 @@ struct ImGuiTabBarSection
 namespace ImGui
 {
     static void             TabBarLayout(ImGuiTabBar* tab_bar);
-    static ImU32            TabBarCalcTabID(ImGuiTabBar* tab_bar, const char* label);
+    static ImU32            TabBarCalcTabID(ImGuiTabBar* tab_bar, const char* label, ImGuiWindow* docked_window);
     static float            TabBarCalcMaxTabWidth();
     static float            TabBarScrollClamp(ImGuiTabBar* tab_bar, float scrolling);
     static void             TabBarScrollToTab(ImGuiTabBar* tab_bar, ImGuiTabItem* tab, ImGuiTabBarSection* sections);
@@ -6925,10 +6917,10 @@ bool    ImGui::BeginTabBar(const char* str_id, ImGuiTabBarFlags flags)
     ImGuiTabBar* tab_bar = g.TabBars.GetOrAddByKey(id);
     ImRect tab_bar_bb = ImRect(window->DC.CursorPos.x, window->DC.CursorPos.y, window->WorkRect.Max.x, window->DC.CursorPos.y + g.FontSize + g.Style.FramePadding.y * 2);
     tab_bar->ID = id;
-    return BeginTabBarEx(tab_bar, tab_bar_bb, flags | ImGuiTabBarFlags_IsFocused);
+    return BeginTabBarEx(tab_bar, tab_bar_bb, flags | ImGuiTabBarFlags_IsFocused, NULL);
 }
 
-bool    ImGui::BeginTabBarEx(ImGuiTabBar* tab_bar, const ImRect& tab_bar_bb, ImGuiTabBarFlags flags)
+bool    ImGui::BeginTabBarEx(ImGuiTabBar* tab_bar, const ImRect& tab_bar_bb, ImGuiTabBarFlags flags, ImGuiDockNode* dock_node)
 {
     ImGuiContext& g = *GImGui;
     ImGuiWindow* window = g.CurrentWindow;
@@ -6953,7 +6945,7 @@ bool    ImGui::BeginTabBarEx(ImGuiTabBar* tab_bar, const ImRect& tab_bar_bb, ImG
 
     // Ensure correct ordering when toggling ImGuiTabBarFlags_Reorderable flag, or when a new tab was added while being not reorderable
     if ((flags & ImGuiTabBarFlags_Reorderable) != (tab_bar->Flags & ImGuiTabBarFlags_Reorderable) || (tab_bar->TabsAddedNew && !(flags & ImGuiTabBarFlags_Reorderable)))
-        if (tab_bar->Tabs.Size > 1)
+        if (tab_bar->Tabs.Size > 1 && (flags & ImGuiTabBarFlags_DockNode) == 0) // FIXME: TabBar with DockNode can now be hybrid
             ImQsort(tab_bar->Tabs.Data, tab_bar->Tabs.Size, sizeof(ImGuiTabItem), TabItemComparerByBeginOrder);
     tab_bar->TabsAddedNew = false;
 
@@ -6979,6 +6971,13 @@ bool    ImGui::BeginTabBarEx(ImGuiTabBar* tab_bar, const ImRect& tab_bar_bb, ImG
     // Draw separator
     const ImU32 col = GetColorU32((flags & ImGuiTabBarFlags_IsFocused) ? ImGuiCol_TabActive : ImGuiCol_TabUnfocusedActive);
     const float y = tab_bar->BarRect.Max.y - 1.0f;
+    if (dock_node != NULL)
+    {
+        const float separator_min_x = dock_node->Pos.x + window->WindowBorderSize;
+        const float separator_max_x = dock_node->Pos.x + dock_node->Size.x - window->WindowBorderSize;
+        window->DrawList->AddLine(ImVec2(separator_min_x, y), ImVec2(separator_max_x, y), col, 1.0f);
+    }
+    else
     {
         const float separator_min_x = tab_bar->BarRect.Min.x - IM_FLOOR(window->WindowPadding.x * 0.5f);
         const float separator_max_x = tab_bar->BarRect.Max.x + IM_FLOOR(window->WindowPadding.x * 0.5f);
@@ -7129,7 +7128,7 @@ static void ImGui::TabBarLayout(ImGuiTabBar* tab_bar)
         // Additionally, when using TabBarAddTab() to manipulate tab bar order we occasionally insert new tabs that don't have a width yet,
         // and we cannot wait for the next BeginTabItem() call. We cannot compute this width within TabBarAddTab() because font size depends on the active window.
         const char* tab_name = tab_bar->GetTabName(tab);
-        const bool has_close_button = (tab->Flags & ImGuiTabItemFlags_NoCloseButton) ? false : true;
+        const bool has_close_button = (tab->Flags & ImGuiTabItemFlags_NoCloseButton) == 0;
         tab->ContentWidth = TabItemCalcSize(tab_name, has_close_button).x;
 
         int section_n = (tab->Flags & ImGuiTabItemFlags_Leading) ? 0 : (tab->Flags & ImGuiTabItemFlags_Trailing) ? 2 : 1;
@@ -7207,6 +7206,7 @@ static void ImGui::TabBarLayout(ImGuiTabBar* tab_bar)
         {
             ImGuiTabItem* tab = &tab_bar->Tabs[section_tab_index + tab_n];
             tab->Offset = tab_offset;
+            tab->NameOffset = -1;
             tab_offset += tab->Width + (tab_n < section->TabCount - 1 ? g.Style.ItemInnerSpacing.x : 0.0f);
         }
         tab_bar->WidthAllTabs += ImMax(section->Width + section->Spacing, 0.0f);
@@ -7214,6 +7214,9 @@ static void ImGui::TabBarLayout(ImGuiTabBar* tab_bar)
         section_tab_index += section->TabCount;
     }
 
+    // Clear name buffers
+    tab_bar->TabsNames.Buf.resize(0);
+
     // If we have lost the selected tab, select the next most recently active one
     if (found_selected_tab_id == false)
         tab_bar->SelectedTabId = 0;
@@ -7224,6 +7227,10 @@ static void ImGui::TabBarLayout(ImGuiTabBar* tab_bar)
     tab_bar->VisibleTabId = tab_bar->SelectedTabId;
     tab_bar->VisibleTabWasSubmitted = false;
 
+    // CTRL+TAB can override visible tab temporarily
+    if (g.NavWindowingTarget != NULL && g.NavWindowingTarget->DockNode && g.NavWindowingTarget->DockNode->TabBar == tab_bar)
+        tab_bar->VisibleTabId = scroll_track_selected_tab_id = g.NavWindowingTarget->ID;
+
     // Update scrolling
     if (scroll_track_selected_tab_id)
         if (ImGuiTabItem* scroll_track_selected_tab = TabBarFindTabByID(tab_bar, scroll_track_selected_tab_id))
@@ -7246,22 +7253,18 @@ static void ImGui::TabBarLayout(ImGuiTabBar* tab_bar)
     tab_bar->ScrollingRectMinX = tab_bar->BarRect.Min.x + sections[0].Width + sections[0].Spacing;
     tab_bar->ScrollingRectMaxX = tab_bar->BarRect.Max.x - sections[2].Width - sections[1].Spacing;
 
-    // Clear name buffers
-    if ((tab_bar->Flags & ImGuiTabBarFlags_DockNode) == 0)
-        tab_bar->TabsNames.Buf.resize(0);
-
     // Actual layout in host window (we don't do it in BeginTabBar() so as not to waste an extra frame)
     ImGuiWindow* window = g.CurrentWindow;
     window->DC.CursorPos = tab_bar->BarRect.Min;
-    ItemSize(ImVec2(tab_bar->WidthAllTabs, tab_bar->BarRect.GetHeight()), tab_bar->FramePadding.y);
-    window->DC.IdealMaxPos.x = ImMax(window->DC.IdealMaxPos.x, tab_bar->BarRect.Min.x + tab_bar->WidthAllTabsIdeal);
+    ItemSize(ImVec2(tab_bar->WidthAllTabsIdeal, tab_bar->BarRect.GetHeight()), tab_bar->FramePadding.y);
 }
 
-// Dockables uses Name/ID in the global namespace. Non-dockable items use the ID stack.
-static ImU32   ImGui::TabBarCalcTabID(ImGuiTabBar* tab_bar, const char* label)
+// Dockable uses Name/ID in the global namespace. Non-dockable items use the ID stack.
+static ImU32   ImGui::TabBarCalcTabID(ImGuiTabBar* tab_bar, const char* label, ImGuiWindow* docked_window)
 {
-    if (tab_bar->Flags & ImGuiTabBarFlags_DockNode)
+    if (docked_window != NULL)
     {
+        IM_ASSERT(tab_bar->Flags & ImGuiTabBarFlags_DockNode);
         ImGuiID id = ImHashStr(label);
         KeepAliveID(id);
         return id;
@@ -7288,6 +7291,38 @@ ImGuiTabItem* ImGui::TabBarFindTabByID(ImGuiTabBar* tab_bar, ImGuiID tab_id)
     return NULL;
 }
 
+// FIXME: See references to #2304 in TODO.txt
+ImGuiTabItem* ImGui::TabBarFindMostRecentlySelectedTabForActiveWindow(ImGuiTabBar* tab_bar)
+{
+    ImGuiTabItem* most_recently_selected_tab = NULL;
+    for (int tab_n = 0; tab_n < tab_bar->Tabs.Size; tab_n++)
+    {
+        ImGuiTabItem* tab = &tab_bar->Tabs[tab_n];
+        if (most_recently_selected_tab == NULL || most_recently_selected_tab->LastFrameSelected < tab->LastFrameSelected)
+            if (tab->Window && tab->Window->WasActive)
+                most_recently_selected_tab = tab;
+    }
+    return most_recently_selected_tab;
+}
+
+// The purpose of this call is to register tab in advance so we can control their order at the time they appear.
+// Otherwise calling this is unnecessary as tabs are appending as needed by the BeginTabItem() function.
+void ImGui::TabBarAddTab(ImGuiTabBar* tab_bar, ImGuiTabItemFlags tab_flags, ImGuiWindow* window)
+{
+    ImGuiContext& g = *GImGui;
+    IM_ASSERT(TabBarFindTabByID(tab_bar, window->ID) == NULL);
+    IM_ASSERT(g.CurrentTabBar != tab_bar);  // Can't work while the tab bar is active as our tab doesn't have an X offset yet, in theory we could/should test something like (tab_bar->CurrFrameVisible < g.FrameCount) but we'd need to solve why triggers the commented early-out assert in BeginTabBarEx() (probably dock node going from implicit to explicit in same frame)
+
+    ImGuiTabItem new_tab;
+    new_tab.ID = window->ID;
+    new_tab.Flags = tab_flags;
+    new_tab.LastFrameVisible = tab_bar->CurrFrameVisible;   // Required so BeginTabBar() doesn't ditch the tab
+    if (new_tab.LastFrameVisible == -1)
+        new_tab.LastFrameVisible = g.FrameCount - 1;
+    new_tab.Window = window;                                // Required so tab bar layout can compute the tab width before tab submission
+    tab_bar->Tabs.push_back(new_tab);
+}
+
 // The *TabId fields be already set by the docking system _before_ the actual TabItem was created, so we clear them regardless.
 void ImGui::TabBarRemoveTab(ImGuiTabBar* tab_bar, ImGuiID tab_id)
 {
@@ -7518,9 +7553,9 @@ bool    ImGui::BeginTabItem(const char* label, bool* p_open, ImGuiTabItemFlags f
         IM_ASSERT_USER_ERROR(tab_bar, "Needs to be called between BeginTabBar() and EndTabBar()!");
         return false;
     }
-    IM_ASSERT(!(flags & ImGuiTabItemFlags_Button)); // BeginTabItem() Can't be used with button flags, use TabItemButton() instead!
+    IM_ASSERT((flags & ImGuiTabItemFlags_Button) == 0);             // BeginTabItem() Can't be used with button flags, use TabItemButton() instead!
 
-    bool ret = TabItemEx(tab_bar, label, p_open, flags);
+    bool ret = TabItemEx(tab_bar, label, p_open, flags, NULL);
     if (ret && !(flags & ImGuiTabItemFlags_NoPushId))
     {
         ImGuiTabItem* tab = &tab_bar->Tabs[tab_bar->LastTabItemIdx];
@@ -7561,10 +7596,10 @@ bool    ImGui::TabItemButton(const char* label, ImGuiTabItemFlags flags)
         IM_ASSERT_USER_ERROR(tab_bar != NULL, "Needs to be called between BeginTabBar() and EndTabBar()!");
         return false;
     }
-    return TabItemEx(tab_bar, label, NULL, flags | ImGuiTabItemFlags_Button | ImGuiTabItemFlags_NoReorder);
+    return TabItemEx(tab_bar, label, NULL, flags | ImGuiTabItemFlags_Button | ImGuiTabItemFlags_NoReorder, NULL);
 }
 
-bool    ImGui::TabItemEx(ImGuiTabBar* tab_bar, const char* label, bool* p_open, ImGuiTabItemFlags flags)
+bool    ImGui::TabItemEx(ImGuiTabBar* tab_bar, const char* label, bool* p_open, ImGuiTabItemFlags flags, ImGuiWindow* docked_window)
 {
     // Layout whole tab bar if not already done
     if (tab_bar->WantLayout)
@@ -7576,7 +7611,7 @@ bool    ImGui::TabItemEx(ImGuiTabBar* tab_bar, const char* label, bool* p_open,
         return false;
 
     const ImGuiStyle& style = g.Style;
-    const ImGuiID id = TabBarCalcTabID(tab_bar, label);
+    const ImGuiID id = TabBarCalcTabID(tab_bar, label, docked_window);
 
     // If the user called us with *p_open == false, we early out and don't render.
     // We make a call to ItemAdd() so that attempts to use a contextual popup menu with an implicit ID won't use an older ID.
@@ -7623,10 +7658,21 @@ bool    ImGui::TabItemEx(ImGuiTabBar* tab_bar, const char* label, bool* p_open,
     const bool is_tab_button = (flags & ImGuiTabItemFlags_Button) != 0;
     tab->LastFrameVisible = g.FrameCount;
     tab->Flags = flags;
+    tab->Window = docked_window;
 
     // Append name with zero-terminator
+    // (regular tabs are permitted in a DockNode tab bar, but window tabs not permitted in a non-DockNode tab bar)
+    if (tab->Window != NULL)
+    {
+        IM_ASSERT(tab_bar->Flags & ImGuiTabBarFlags_DockNode);
+        tab->NameOffset = -1;
+    }
+    else
+    {
+        IM_ASSERT(tab->Window == NULL);
         tab->NameOffset = (ImS16)tab_bar->TabsNames.size();
-    tab_bar->TabsNames.append(label, label + strlen(label) + 1);
+        tab_bar->TabsNames.append(label, label + strlen(label) + 1); // Append name _with_ the zero-terminator.
+    }
 
     // Update selected tab
     if (tab_appearing && (tab_bar->Flags & ImGuiTabBarFlags_AutoSelectNewTabs) && tab_bar->NextSelectedTabId == 0)
@@ -7644,7 +7690,7 @@ bool    ImGui::TabItemEx(ImGuiTabBar* tab_bar, const char* label, bool* p_open,
         tab_bar->VisibleTabWasSubmitted = true;
 
     // On the very first frame of a tab bar we let first tab contents be visible to minimize appearing glitches
-    if (!tab_contents_visible && tab_bar->SelectedTabId == 0 && tab_bar_appearing)
+    if (!tab_contents_visible && tab_bar->SelectedTabId == 0 && tab_bar_appearing && docked_window == NULL)
         if (tab_bar->Tabs.Size == 1 && !(tab_bar->Flags & ImGuiTabBarFlags_AutoSelectNewTabs))
             tab_contents_visible = true;
 
@@ -7695,7 +7741,7 @@ bool    ImGui::TabItemEx(ImGuiTabBar* tab_bar, const char* label, bool* p_open,
 
     // Click to Select a tab
     ImGuiButtonFlags button_flags = ((is_tab_button ? ImGuiButtonFlags_PressedOnClickRelease : ImGuiButtonFlags_PressedOnClick) | ImGuiButtonFlags_AllowItemOverlap);
-    if (g.DragDropActive)
+    if (g.DragDropActive && !g.DragDropPayload.IsDataType(IMGUI_PAYLOAD_TYPE_WINDOW))
         button_flags |= ImGuiButtonFlags_PressedOnDragDropHold;
     bool hovered, held;
     bool pressed = ButtonBehavior(bb, id, &hovered, &held, button_flags);
@@ -7703,27 +7749,76 @@ bool    ImGui::TabItemEx(ImGuiTabBar* tab_bar, const char* label, bool* p_open,
         tab_bar->NextSelectedTabId = id;
     hovered |= (g.HoveredId == id);
 
+    // Transfer active id window so the active id is not owned by the dock host (as StartMouseMovingWindow()
+    // will only do it on the drag). This allows FocusWindow() to be more conservative in how it clears active id.
+    if (held && docked_window && g.ActiveId == id && g.ActiveIdIsJustActivated)
+        g.ActiveIdWindow = docked_window;
+
     // Allow the close button to overlap unless we are dragging (in which case we don't want any overlapping tabs to be hovered)
-    if (g.ActiveId != id)
+    if (!held)
         SetItemAllowOverlap();
 
-    // Drag and drop: re-order tabs
-    if (held && !tab_appearing && IsMouseDragging(0))
+    // Drag and drop a single floating window node moves it
+    ImGuiDockNode* node = docked_window ? docked_window->DockNode : NULL;
+    const bool single_floating_window_node = node && node->IsFloatingNode() && (node->Windows.Size == 1);
+    if (held && single_floating_window_node && IsMouseDragging(0, 0.0f))
     {
-        if (!g.DragDropActive && (tab_bar->Flags & ImGuiTabBarFlags_Reorderable))
+        // Move
+        StartMouseMovingWindow(docked_window);
+    }
+    else if (held && !tab_appearing && IsMouseDragging(0))
+    {
+        // Drag and drop: re-order tabs
+        float drag_distance_from_edge_x = 0.0f;
+        if (!g.DragDropActive && ((tab_bar->Flags & ImGuiTabBarFlags_Reorderable) || (docked_window != NULL)))
         {
             // While moving a tab it will jump on the other side of the mouse, so we also test for MouseDelta.x
             if (g.IO.MouseDelta.x < 0.0f && g.IO.MousePos.x < bb.Min.x)
             {
+                drag_distance_from_edge_x = bb.Min.x - g.IO.MousePos.x;
                 if (tab_bar->Flags & ImGuiTabBarFlags_Reorderable)
                     TabBarQueueReorder(tab_bar, tab, -1);
             }
             else if (g.IO.MouseDelta.x > 0.0f && g.IO.MousePos.x > bb.Max.x)
             {
+                drag_distance_from_edge_x = g.IO.MousePos.x - bb.Max.x;
                 if (tab_bar->Flags & ImGuiTabBarFlags_Reorderable)
                     TabBarQueueReorder(tab_bar, tab, +1);
             }
         }
+
+        // Extract a Dockable window out of it's tab bar
+        if (docked_window != NULL && !(docked_window->Flags & ImGuiWindowFlags_NoMove))
+        {
+            // We use a variable threshold to distinguish dragging tabs within a tab bar and extracting them out of the tab bar
+            bool undocking_tab = (g.DragDropActive && g.DragDropPayload.SourceId == id);
+
+            if (!undocking_tab) //&& (!g.IO.ConfigDockingWithShift || g.IO.KeyShift)
+            {
+                float threshold_base = g.FontSize;
+                //float threshold_base = g.IO.ConfigDockingWithShift ? g.FontSize * 0.5f : g.FontSize;
+                float threshold_x = (threshold_base * 2.2f);
+                float threshold_y = (threshold_base * 1.5f) + ImClamp((ImFabs(g.IO.MouseDragMaxDistanceAbs[0].x) - threshold_base * 2.0f) * 0.20f, 0.0f, threshold_base * 4.0f);
+                //GetForegroundDrawList()->AddRect(ImVec2(bb.Min.x - threshold_x, bb.Min.y - threshold_y), ImVec2(bb.Max.x + threshold_x, bb.Max.y + threshold_y), IM_COL32_WHITE); // [DEBUG]
+
+                float distance_from_edge_y = ImMax(bb.Min.y - g.IO.MousePos.y, g.IO.MousePos.y - bb.Max.y);
+                if (distance_from_edge_y >= threshold_y)
+                    undocking_tab = true;
+                else if (drag_distance_from_edge_x > threshold_x)
+                    if ((tab_bar->ReorderRequestDir < 0 && tab_bar->GetTabOrder(tab) == 0) || (tab_bar->ReorderRequestDir > 0 && tab_bar->GetTabOrder(tab) == tab_bar->Tabs.Size - 1))
+                        undocking_tab = true;
+            }
+
+            if (undocking_tab)
+            {
+                // Undock
+                DockContextQueueUndockWindow(&g, docked_window);
+                g.MovingWindow = docked_window;
+                SetActiveID(g.MovingWindow->MoveId, g.MovingWindow);
+                g.ActiveIdClickOffset -= g.MovingWindow->Pos - bb.Min;
+                g.ActiveIdNoClearOnFocusLoss = true;
+            }
+        }
     }
 
 #if 0
@@ -7789,10 +7884,20 @@ void    ImGui::SetTabItemClosed(const char* label)
     if (is_within_manual_tab_bar)
     {
         ImGuiTabBar* tab_bar = g.CurrentTabBar;
-        ImGuiID tab_id = TabBarCalcTabID(tab_bar, label);
+        ImGuiID tab_id = TabBarCalcTabID(tab_bar, label, NULL);
         if (ImGuiTabItem* tab = TabBarFindTabByID(tab_bar, tab_id))
             tab->WantClose = true; // Will be processed by next call to TabBarLayout()
     }
+    else if (ImGuiWindow* window = FindWindowByName(label))
+    {
+        if (window->DockIsActive)
+            if (ImGuiDockNode* node = window->DockNode)
+            {
+                ImGuiID tab_id = TabBarCalcTabID(node->TabBar, label, window);
+                TabBarRemoveTab(node->TabBar, tab_id);
+                window->DockTabWantClose = true;
+            }
+    }
 }
 
 ImVec2 ImGui::TabItemCalcSize(const char* label, bool has_close_button)
@@ -7816,7 +7921,7 @@ void ImGui::TabItemBackground(ImDrawList* draw_list, const ImRect& bb, ImGuiTabI
     IM_ASSERT(width > 0.0f);
     const float rounding = ImMax(0.0f, ImMin((flags & ImGuiTabItemFlags_Button) ? g.Style.FrameRounding : g.Style.TabRounding, width * 0.5f - 1.0f));
     const float y1 = bb.Min.y + 1.0f;
-    const float y2 = bb.Max.y - 1.0f;
+    const float y2 = bb.Max.y + ((flags & ImGuiTabItemFlags_Preview) ? 0.0f : -1.0f);
     draw_list->PathLineTo(ImVec2(bb.Min.x, y2));
     draw_list->PathArcToFast(ImVec2(bb.Min.x + rounding, y1 + rounding), rounding, 6, 9);
     draw_list->PathArcToFast(ImVec2(bb.Max.x - rounding, y1 + rounding), rounding, 9, 12);

misc/freetype/README.md

@@ -104,7 +104,8 @@ struct FreeTypeTest
     // Call to draw interface
     void ShowFreetypeOptionsWindow()
     {
-        ImGui::Begin("FreeType Options");
+        if (!ImGui::Begin("FreeType Options"))
+            return;
         ImGui::ShowFontSelector("Fonts");
         WantRebuild |= ImGui::RadioButton("FreeType", (int*)&BuildMode, FontBuildMode_FreeType);
         ImGui::SameLine();

misc/natvis/imgui.natvis

@@ -46,4 +46,8 @@
   <DisplayString>{{Name {Name,s} Active {(Active||WasActive)?1:0,d} Child {(Flags &amp; 0x01000000)?1:0,d} Popup {(Flags &amp; 0x04000000)?1:0,d} Hidden {(Hidden)?1:0,d}}</DisplayString>
 </Type>
 
+<Type Name="ImGuiDockNode">
+  <DisplayString>{{ID {ID,x} Pos=({Pos.x,g} {Pos.y,g}) Size=({Size.x,g} {Size.y,g}) Parent {(ParentNode==0)?0:ParentNode->ID,x} Childs {(ChildNodes[0] != 0)+(ChildNodes[1] != 0)} Windows {Windows.Size}  }</DisplayString>
+</Type>
+  
 </AutoVisualizer>