Synced/merged minor cruft from docking branch to minimize drift. AFAIK the only meaningful no-op change is that the call UpdateHoveredWindowAndCaptureFlags() was moved above UpdateMouseMovingNewFrame() to match what docking branch has been doing for a while.

docs/TODO.txt

@@ -9,6 +9,7 @@ It's mostly a bunch of personal notes, probably incomplete. Feel free to query i
  - doc/test: checklist app to verify binding/integration of imgui (test inputs, rendering, callback, etc.).
  - doc/tips: tips of the day: website? applet in imgui_club?
 
+ - window: preserve/restore relative focus ordering (persistent or not) (#2304) -> also see docking reference to same #.
  - window: calling SetNextWindowSize() every frame with <= 0 doesn't do anything, may be useful to allow (particularly when used for a single axis). (#690)
  - window: add a way for very transient windows (non-saved, temporary overlay over hundreds of objects) to "clean" up from the global window list. perhaps a lightweight explicit cleanup pass.
  - window: auto-fit feedback loop when user relies on any dynamic layout (window width multiplier, column) appears weird to end-user. clarify.

examples/example_glfw_opengl3/main.cpp

@@ -171,14 +171,12 @@ int main(int, char**)
         // Rendering
         ImGui::Render();
         int display_w, display_h;
-        glfwMakeContextCurrent(window);
         glfwGetFramebufferSize(window, &display_w, &display_h);
         glViewport(0, 0, display_w, display_h);
         glClearColor(clear_color.x, clear_color.y, clear_color.z, clear_color.w);
         glClear(GL_COLOR_BUFFER_BIT);
         ImGui_ImplOpenGL3_RenderDrawData(ImGui::GetDrawData());
 
-        glfwMakeContextCurrent(window);
         glfwSwapBuffers(window);
     }
 

examples/example_sdl_opengl2/example_sdl_opengl2.vcxproj

@@ -19,7 +19,7 @@
     </ProjectConfiguration>
   </ItemGroup>
   <PropertyGroup Label="Globals">
-    <ProjectGuid>{94E991D0-790A-4DAF-B442-AAADE3233C75}</ProjectGuid>
+    <ProjectGuid>{2AE17FDE-F7F3-4CAC-ADAB-0710EDA4F741}</ProjectGuid>
     <RootNamespace>example_sdl_opengl2</RootNamespace>
     <WindowsTargetPlatformVersion>8.1</WindowsTargetPlatformVersion>
   </PropertyGroup>

examples/example_sdl_opengl2/main.cpp

@@ -31,6 +31,7 @@ int main(int, char**)
     SDL_WindowFlags window_flags = (SDL_WindowFlags)(SDL_WINDOW_OPENGL | SDL_WINDOW_RESIZABLE | SDL_WINDOW_ALLOW_HIGHDPI);
     SDL_Window* window = SDL_CreateWindow("Dear ImGui SDL2+OpenGL example", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, 1280, 720, window_flags);
     SDL_GLContext gl_context = SDL_GL_CreateContext(window);
+    SDL_GL_MakeCurrent(window, gl_context);
     SDL_GL_SetSwapInterval(1); // Enable vsync
 
     // Setup Dear ImGui context

examples/example_sdl_opengl3/main.cpp

@@ -55,6 +55,7 @@ int main(int, char**)
     SDL_WindowFlags window_flags = (SDL_WindowFlags)(SDL_WINDOW_OPENGL | SDL_WINDOW_RESIZABLE | SDL_WINDOW_ALLOW_HIGHDPI);
     SDL_Window* window = SDL_CreateWindow("Dear ImGui SDL2+OpenGL3 example", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, 1280, 720, window_flags);
     SDL_GLContext gl_context = SDL_GL_CreateContext(window);
+    SDL_GL_MakeCurrent(window, gl_context);
     SDL_GL_SetSwapInterval(1); // Enable vsync
 
     // Initialize OpenGL loader
@@ -170,7 +171,6 @@ int main(int, char**)
 
         // Rendering
         ImGui::Render();
-        SDL_GL_MakeCurrent(window, gl_context);
         glViewport(0, 0, (int)io.DisplaySize.x, (int)io.DisplaySize.y);
         glClearColor(clear_color.x, clear_color.y, clear_color.z, clear_color.w);
         glClear(GL_COLOR_BUFFER_BIT);

examples/example_win32_directx12/main.cpp

@@ -333,9 +333,9 @@ void CleanupDeviceD3D()
 
 void CreateRenderTarget()
 {
-    ID3D12Resource* pBackBuffer;
     for (UINT i = 0; i < NUM_BACK_BUFFERS; i++)
     {
+        ID3D12Resource* pBackBuffer = NULL;
         g_pSwapChain->GetBuffer(i, IID_PPV_ARGS(&pBackBuffer));
         g_pd3dDevice->CreateRenderTargetView(pBackBuffer, NULL, g_mainRenderTargetDescriptor[i]);
         g_mainRenderTargetResource[i] = pBackBuffer;

examples/imgui_impl_dx10.cpp

@@ -146,7 +146,7 @@ void ImGui_ImplDX10_RenderDrawData(ImDrawData* draw_data)
     g_pIB->Unmap();
 
     // 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).
+    // 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.
     {
         void* mapped_resource;
         if (g_pVertexConstantBuffer->Map(D3D10_MAP_WRITE_DISCARD, 0, &mapped_resource) != S_OK)
@@ -486,6 +486,7 @@ void    ImGui_ImplDX10_InvalidateDeviceObjects()
 
 bool    ImGui_ImplDX10_Init(ID3D10Device* device)
 {
+    // Setup back-end capabilities flags
     ImGuiIO& io = ImGui::GetIO();
     io.BackendRendererName = "imgui_impl_dx10";
     io.BackendFlags |= ImGuiBackendFlags_RendererHasVtxOffset;  // We can honor the ImDrawCmd::VtxOffset field, allowing for large meshes.

examples/imgui_impl_dx11.cpp

@@ -148,7 +148,7 @@ void ImGui_ImplDX11_RenderDrawData(ImDrawData* draw_data)
     ctx->Unmap(g_pIB, 0);
 
     // 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).
+    // 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.
     {
         D3D11_MAPPED_SUBRESOURCE mapped_resource;
         if (ctx->Map(g_pVertexConstantBuffer, 0, D3D11_MAP_WRITE_DISCARD, 0, &mapped_resource) != S_OK)
@@ -493,6 +493,7 @@ void    ImGui_ImplDX11_InvalidateDeviceObjects()
 
 bool    ImGui_ImplDX11_Init(ID3D11Device* device, ID3D11DeviceContext* device_context)
 {
+    // Setup back-end capabilities flags
     ImGuiIO& io = ImGui::GetIO();
     io.BackendRendererName = "imgui_impl_dx11";
     io.BackendFlags |= ImGuiBackendFlags_RendererHasVtxOffset;  // We can honor the ImDrawCmd::VtxOffset field, allowing for large meshes.

examples/imgui_impl_dx12.cpp

@@ -605,6 +605,7 @@ void    ImGui_ImplDX12_InvalidateDeviceObjects()
 bool ImGui_ImplDX12_Init(ID3D12Device* device, int num_frames_in_flight, DXGI_FORMAT rtv_format,
                          D3D12_CPU_DESCRIPTOR_HANDLE font_srv_cpu_desc_handle, D3D12_GPU_DESCRIPTOR_HANDLE font_srv_gpu_desc_handle)
 {
+    // Setup back-end capabilities flags
     ImGuiIO& io = ImGui::GetIO();
     io.BackendRendererName = "imgui_impl_dx12";
     io.BackendFlags |= ImGuiBackendFlags_RendererHasVtxOffset;  // We can honor the ImDrawCmd::VtxOffset field, allowing for large meshes.

examples/imgui_impl_dx9.cpp

@@ -80,7 +80,7 @@ static void ImGui_ImplDX9_SetupRenderState(ImDrawData* draw_data)
     g_pd3dDevice->SetSamplerState(0, D3DSAMP_MAGFILTER, D3DTEXF_LINEAR);
 
     // Setup orthographic projection matrix
-    // Our visible imgui space lies from draw_data->DisplayPos (top left) to draw_data->DisplayPos+data_data->DisplaySize (bottom right).
+    // 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.
     // Being agnostic of whether <d3dx9.h> or <DirectXMath.h> can be used, we aren't relying on D3DXMatrixIdentity()/D3DXMatrixOrthoOffCenterLH() or DirectX::XMMatrixIdentity()/DirectX::XMMatrixOrthographicOffCenterLH()
     {
         float L = draw_data->DisplayPos.x + 0.5f;
@@ -218,6 +218,7 @@ void ImGui_ImplDX9_RenderDrawData(ImDrawData* draw_data)
 
 bool ImGui_ImplDX9_Init(IDirect3DDevice9* device)
 {
+    // Setup back-end capabilities flags
     ImGuiIO& io = ImGui::GetIO();
     io.BackendRendererName = "imgui_impl_dx9";
     io.BackendFlags |= ImGuiBackendFlags_RendererHasVtxOffset;  // We can honor the ImDrawCmd::VtxOffset field, allowing for large meshes.

examples/imgui_impl_dx9.h

@@ -19,5 +19,5 @@ IMGUI_IMPL_API void     ImGui_ImplDX9_NewFrame();
 IMGUI_IMPL_API void     ImGui_ImplDX9_RenderDrawData(ImDrawData* draw_data);
 
 // Use if you want to reset your rendering device without losing ImGui state.
-IMGUI_IMPL_API void     ImGui_ImplDX9_InvalidateDeviceObjects();
 IMGUI_IMPL_API bool     ImGui_ImplDX9_CreateDeviceObjects();
+IMGUI_IMPL_API void     ImGui_ImplDX9_InvalidateDeviceObjects();

examples/imgui_impl_glfw.cpp

@@ -56,7 +56,7 @@ enum GlfwClientApi
     GlfwClientApi_OpenGL,
     GlfwClientApi_Vulkan
 };
-static GLFWwindow*          g_Window = NULL;
+static GLFWwindow*          g_Window = NULL;    // Main window
 static GlfwClientApi        g_ClientApi = GlfwClientApi_Unknown;
 static double               g_Time = 0.0;
 static bool                 g_MouseJustPressed[5] = { false, false, false, false, false };

examples/imgui_impl_opengl2.cpp

@@ -57,6 +57,7 @@ static GLuint       g_FontTexture = 0;
 // Functions
 bool    ImGui_ImplOpenGL2_Init()
 {
+    // Setup back-end capabilities flags
     ImGuiIO& io = ImGui::GetIO();
     io.BackendRendererName = "imgui_impl_opengl2";
     return true;
@@ -98,7 +99,7 @@ static void ImGui_ImplOpenGL2_SetupRenderState(ImDrawData* draw_data, int fb_wid
     //  glUseProgram(last_program)
 
     // 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). DisplayMin is typically (0,0) for single viewport apps.
+    // 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.
     glViewport(0, 0, (GLsizei)fb_width, (GLsizei)fb_height);
     glMatrixMode(GL_PROJECTION);
     glPushMatrix();

examples/imgui_impl_opengl3.cpp

@@ -122,6 +122,7 @@ static unsigned int g_VboHandle = 0, g_ElementsHandle = 0;
 // Functions
 bool    ImGui_ImplOpenGL3_Init(const char* glsl_version)
 {
+    // Setup back-end capabilities flags
     ImGuiIO& io = ImGui::GetIO();
     io.BackendRendererName = "imgui_impl_opengl3";
 #if IMGUI_IMPL_OPENGL_HAS_DRAW_WITH_BASE_VERTEX
@@ -177,7 +178,7 @@ static void ImGui_ImplOpenGL3_SetupRenderState(ImDrawData* draw_data, int fb_wid
 #endif
 
     // 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). DisplayMin is typically (0,0) for single viewport apps.
+    // 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.
     glViewport(0, 0, (GLsizei)fb_width, (GLsizei)fb_height);
     float L = draw_data->DisplayPos.x;
     float R = draw_data->DisplayPos.x + draw_data->DisplaySize.x;

examples/imgui_impl_sdl.cpp

@@ -43,7 +43,6 @@
 #include "imgui_impl_sdl.h"
 
 // SDL
-// (the multi-viewports feature requires SDL features supported from SDL 2.0.5+)
 #include <SDL.h>
 #include <SDL_syswm.h>
 #if defined(__APPLE__)

examples/imgui_impl_vulkan.cpp

@@ -293,7 +293,7 @@ static void ImGui_ImplVulkan_SetupRenderState(ImDrawData* draw_data, VkCommandBu
     }
 
     // Setup scale and translation:
-    // Our visible imgui space lies from draw_data->DisplayPos (top left) to draw_data->DisplayPos+data_data->DisplaySize (bottom right). DisplayMin is typically (0,0) for single viewport apps.
+    // Our visible imgui space lies from draw_data->DisplayPps (top left) to draw_data->DisplayPos+data_data->DisplaySize (bottom right). DisplayPos is (0,0) for single viewport apps.
     {
         float scale[2];
         scale[0] = 2.0f / draw_data->DisplaySize.x;
@@ -803,6 +803,7 @@ void    ImGui_ImplVulkan_DestroyDeviceObjects()
 
 bool    ImGui_ImplVulkan_Init(ImGui_ImplVulkan_InitInfo* info, VkRenderPass render_pass)
 {
+    // Setup back-end capabilities flags
     ImGuiIO& io = ImGui::GetIO();
     io.BackendRendererName = "imgui_impl_vulkan";
     io.BackendFlags |= ImGuiBackendFlags_RendererHasVtxOffset;  // We can honor the ImDrawCmd::VtxOffset field, allowing for large meshes.

imgui.cpp

@@ -3575,9 +3575,12 @@ void ImGui::NewFrame()
     g.FramerateSecPerFrameIdx = (g.FramerateSecPerFrameIdx + 1) % IM_ARRAYSIZE(g.FramerateSecPerFrame);
     g.IO.Framerate = (g.FramerateSecPerFrameAccum > 0.0f) ? (1.0f / (g.FramerateSecPerFrameAccum / (float)IM_ARRAYSIZE(g.FramerateSecPerFrame))) : FLT_MAX;
 
+    // Find hovered window
+    // (needs to be before UpdateMouseMovingWindowNewFrame so we fill g.HoveredWindowUnderMovingWindow on the mouse release frame)
+    UpdateHoveredWindowAndCaptureFlags();
+
     // Handle user moving window with mouse (at the beginning of the frame to avoid input lag or sheering)
     UpdateMouseMovingWindowNewFrame();
-    UpdateHoveredWindowAndCaptureFlags();
 
     // Background darkening/whitening
     if (GetFrontMostPopupModal() != NULL || (g.NavWindowingTarget != NULL && g.NavWindowingHighlightAlpha > 0.0f))
@@ -4722,7 +4725,7 @@ static ImVec2 CalcSizeAutoFit(ImGuiWindow* window, const ImVec2& size_contents)
     }
     else
     {
-        // Maximum window size is determined by the display size
+        // Maximum window size is determined by the viewport size or monitor size
         const bool is_popup = (window->Flags & ImGuiWindowFlags_Popup) != 0;
         const bool is_menu = (window->Flags & ImGuiWindowFlags_ChildMenu) != 0;
         ImVec2 size_min = style.WindowMinSize;
@@ -5081,7 +5084,7 @@ void ImGui::RenderWindowTitleBarContents(ImGuiWindow* window, const ImRect& titl
     const bool has_close_button = (p_open != NULL);
     const bool has_collapse_button = !(flags & ImGuiWindowFlags_NoCollapse);
 
-    // Close & collapse button are on the Menu NavLayer and don't default focus (unless there's nothing else on that layer)
+    // Close & Collapse button are on the Menu NavLayer and don't default focus (unless there's nothing else on that layer)
     const ImGuiItemFlags item_flags_backup = window->DC.ItemFlags;
     window->DC.ItemFlags |= ImGuiItemFlags_NoNavDefaultFocus;
     window->DC.NavLayerCurrent = ImGuiNavLayer_Menu;
@@ -5451,7 +5454,8 @@ bool ImGui::Begin(const char* name, bool* p_open, ImGuiWindowFlags flags)
         else if ((flags & ImGuiWindowFlags_Tooltip) != 0 && !window_pos_set_by_api && !window_is_child_tooltip)
             window->Pos = FindBestWindowPosForPopup(window);
 
-        // Clamp position/size so it stays visible
+        // Clamp position/size so window stays visible within its viewport or monitor
+
         // Ignore zero-sized display explicitly to avoid losing positions if a window manager reports zero-sized window when initializing or minimizing.
         ImRect viewport_rect(GetViewportRect());
         if (!window_pos_set_by_api && !(flags & ImGuiWindowFlags_ChildWindow) && window->AutoFitFramesX <= 0 && window->AutoFitFramesY <= 0)
@@ -8701,6 +8705,7 @@ void ImGui::PushColumnsBackground()
     window->DrawList->ChannelsSetCurrent(0);
     int cmd_size = window->DrawList->CmdBuffer.Size;
     PushClipRect(columns->HostClipRect.Min, columns->HostClipRect.Max, false); 
+    IM_UNUSED(cmd_size);
     IM_ASSERT(cmd_size == window->DrawList->CmdBuffer.Size); // Being in channel 0 this should not have created an ImDrawCmd
 }
 

imgui_widgets.cpp

@@ -463,7 +463,8 @@ bool ImGui::ButtonBehavior(const ImRect& bb, ImGuiID id, bool* out_hovered, bool
         flags |= ImGuiButtonFlags_PressedOnClickRelease;
 
     ImGuiWindow* backup_hovered_window = g.HoveredWindow;
-    if ((flags & ImGuiButtonFlags_FlattenChildren) && g.HoveredRootWindow == window)
+    const bool flatten_hovered_children = (flags & ImGuiButtonFlags_FlattenChildren) && g.HoveredRootWindow == window;
+    if (flatten_hovered_children)
         g.HoveredWindow = window;
 
 #ifdef IMGUI_ENABLE_TEST_ENGINE
@@ -491,7 +492,7 @@ bool ImGui::ButtonBehavior(const ImRect& bb, ImGuiID id, bool* out_hovered, bool
             }
         }
 
-    if ((flags & ImGuiButtonFlags_FlattenChildren) && g.HoveredRootWindow == window)
+    if (flatten_hovered_children)
         g.HoveredWindow = backup_hovered_window;
 
     // AllowOverlap mode (rarely used) requires previous frame HoveredId to be null or to match. This allows using patterns where a later submitted widget overlaps a previous one.
@@ -6454,7 +6455,8 @@ 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);
-        tab->WidthContents = TabItemCalcSize(tab_name, (tab->Flags & ImGuiTabItemFlags_NoCloseButton) ? false : true).x;
+        const bool has_close_button = (tab->Flags & ImGuiTabItemFlags_NoCloseButton) ? false : true;
+        tab->WidthContents = TabItemCalcSize(tab_name, has_close_button).x;
 
         width_total_contents += (tab_n > 0 ? g.Style.ItemInnerSpacing.x : 0.0f) + tab->WidthContents;