Merge branch 'master' into docking

# Conflicts:
#	imgui.cpp
#	imgui_internal.h

docs/CHANGELOG.txt

@@ -8,6 +8,7 @@ Changes to the examples/bindings are included within the individual .cpp files i
 RELEASE NOTES:                  https://github.com/ocornut/imgui/releases
 REPORT ISSUES, ASK QUESTIONS:   https://github.com/ocornut/imgui/issues
 COMMITS HISTORY:                https://github.com/ocornut/imgui/commits/master
+FAQ                             https://www.dearimgui.org/faq/
 
 WHEN TO UPDATE?
 
@@ -103,6 +104,7 @@ Other changes:
 -----------------------------------------------------------------------
 
 Breaking Changes:
+
 - Removed redirecting functions/enums names that were marked obsolete in 1.53 (December 2017):
   - ShowTestWindow()                    -> use ShowDemoWindow()
   - IsRootWindowFocused()               -> use IsWindowFocused(ImGuiFocusedFlags_RootWindow)
@@ -132,8 +134,11 @@ Breaking Changes:
   adding multiple points into it, you may need to fix your initial value.
 
 Other Changes:
+
 - Inputs: Added ImGuiMouseButton enum for convenience (e.g. ImGuiMouseButton_Right=1).
   We forever guarantee that the existing value will not changes so existing code is free to use 0/1/2.
+- Nav: Fixed a bug where the initial CTRL-Tab press while in a child window sometimes selected
+  the current root window instead of always selecting the previous root window. (#787)
 - ColorEdit: Fix label alignment when using ImGuiColorEditFlags_NoInputs. (#2955) [@rokups]
 - ColorEdit: In HSV display of a RGB stored value, attempt to locally preserve Saturation
   when Value==0.0 (similar to changes done in 1.73 for Hue). Removed Hue editing lock since
@@ -142,18 +147,23 @@ Other Changes:
 - ColorEdit: "Copy As" content-menu tool shows hex values both with/without alpha when available.
 - MenuBar: Fix minor clipping issue where occasionally a menu text can overlap the right-most border.
 - Window: Fix SetNextWindowBgAlpha(1.0f) failing to override alpha component. (#3007) [@Albog]
+- Window: When testing for the presence of the ImGuiWindowFlags_NoBringToFrontOnFocus flag we
+  test both the focused/clicked window (which could be a child window) and the root window.
 - ImDrawList: AddCircle(), AddCircleFilled() API can now auto-tessellate when provided a segment
   count of zero. Alter tessellation quality with 'style.CircleSegmentMaxError'. [@ShironekoBen]
 - ImDrawList: Add AddNgon(), AddNgonFilled() API with a guarantee on the explicit segment count.
   In the current branch they are essentially the same as AddCircle(), AddCircleFilled() but as
   we will rework the circle rendering functions to use textures and automatic segment count
   selection, those new api can fill a gap. [@ShironekoBen]
+- Columns: ImDrawList::Channels* functions now work inside columns. Added extra comments to
+  suggest using user-owned ImDrawListSplitter instead of ImDrawList functions. [@rokups]
 - Misc: Added ImGuiMouseCursor_NotAllowed enum so it can be used by more shared widgets. [@rokups]
 - Misc: Disable format checks when using stb_printf, to allow using extra formats.
   Made IMGUI_USE_STB_SPRINTF a properly documented imconfig.h flag. (#2954) [@loicmolinari]
 - Misc: Added misc/single_file/imgui_single_file.h, We use this to validate compiling all *.cpp
   files in a same compilation unit. Actual users of that technique (also called "Unity builds")
   can generally provide this themselves, so we don't really recommend you use this. [@rokups]
+- CI: Added PVS-Studio static analysis on the continuous-integration server. [@rokups]
 - Backends: GLFW, SDL, Win32, OSX, Allegro: Added support for ImGuiMouseCursor_NotAllowed. [@rokups]
 - Backends: GLFW: Added support for the missing mouse cursors newly added in GLFW 3.4+. [@rokups]
 - Backends: SDL: Wayland: use SDL_GetMouseState (because there is no global mouse state available
@@ -167,13 +177,14 @@ Other Changes:
   the later may be problematic if compiling with recent Windows SDK and you want your app to run
   on Windows 7. You can instead try linking with Xinput9_1_0.lib instead. (#2716)
 - Backends: Glut: Improved FreeGLUT support for MinGW. (#3004) [@podsvirov]
-- CI: Added PVS-Studio static analysis on the continuous-integration server. [@rokups]
+- Backends: Emscripten: Avoid forcefully setting IMGUI_DISABLE_FILE_FUNCTIONS. (#3005) [@podsvirov]
-- Examples: Explicitly adding -DIMGUI_IMPL_OPENGL_LOADER_GL3W to Makefile to match linking
+- Examples: OpenGL: Explicitly adding -DIMGUI_IMPL_OPENGL_LOADER_GL3W to Makefile to match linking
   settings (otherwise if another loader such as Glew is accessible, the OpenGL3 backend might
   automatically use it). (#2919, #2798)
+- Examples: OpenGL: Added support for glbindings OpenGL loader. (#2870) [@rokups]
+- Examples: Emscripten: Demonstrating embedding fonts in Makefile and code. (#2953) [@Oipo]
 - Examples: Metal: Wrapped main loop in @autoreleasepool block to ensure allocations get freed
   even if underlying system event loop gets paused due to app nap. (#2910, #2917) [@bear24rw]
-- Examples: Added support for glbindings OpenGL loader. (#2870) [@rokups]
 
 
 -----------------------------------------------------------------------
@@ -183,6 +194,7 @@ Other Changes:
 Decorated log: https://github.com/ocornut/imgui/releases/tag/v1.74
 
 Breaking Changes:
+
 - Removed redirecting functions/enums names that were marked obsolete in 1.52 (October 2017):
   - Begin() [old 5 args version]     -> use Begin() [3 args], use SetNextWindowSize() SetNextWindowBgAlpha() if needed
   - IsRootWindowOrAnyChildHovered()  -> use IsWindowHovered(ImGuiHoveredFlags_RootAndChildWindows)
@@ -207,6 +219,7 @@ Breaking Changes:
   The value is unused in master branch but will be used by the multi-viewport feature. (#2851) [@obfuscate]
 
 Other Changes:
+
 - InputText, Nav: Fixed Home/End key broken when activating Keyboard Navigation. (#787)
 - InputText: Filter out ASCII 127 (DEL) emitted by low-level OSX layer, as we are using the Key value. (#2578)
 - Layout: Fixed a couple of subtle bounding box vertical positioning issues relating to the handling of text
@@ -339,6 +352,7 @@ Other Changes:
 Decorated log: https://github.com/ocornut/imgui/releases/tag/v1.72
 
 Breaking Changes:
+
 - Removed redirecting functions/enums names that were marked obsolete in 1.51 (June 2017):
   - ImGuiCol_Column*, ImGuiSetCond_* enums.
   - IsItemHoveredRect(), IsPosHoveringAnyWindow(), IsMouseHoveringAnyWindow(), IsMouseHoveringWindow() functions.
@@ -350,6 +364,7 @@ Breaking Changes:
   Kept redirection function (will obsolete). (#581, #324)
 
 Other Changes:
+
 - Scrolling: Made mouse-wheel scrolling lock the underlying window until the mouse is moved again or
   until a short delay expires (~2 seconds). This allow uninterrupted scroll even if child windows are
   passing under the mouse cursor. (#2604)
@@ -422,6 +437,7 @@ Other Changes:
 Decorated log: https://github.com/ocornut/imgui/releases/tag/v1.71
 
 Breaking Changes:
+
 - IO: changed AddInputCharacter(unsigned short c) signature to AddInputCharacter(unsigned int c).
 - Renamed SetNextTreeNodeOpen() to SetNextItemOpen(). Kept inline redirection function (will obsolete).
 - Window: rendering of child windows outer decorations (e.g. bg color, border, scrollbars) is now
@@ -432,6 +448,7 @@ Breaking Changes:
   to the creation of overlapping child windows. Please reach out if you are affected by this change!
 
 Other Changes:
+
 - Window: clarified behavior of SetNextWindowContentSize(). Content size is defined as the size available
   after removal of WindowPadding on each sides. So SetNextWindowContentSize(ImVec2(100,100)) + auto-resize
   will always allow submitting a 100x100 item without creating a scrollbar, regarding of WindowPadding.
@@ -504,6 +521,7 @@ Other Changes:
 Decorated log: https://github.com/ocornut/imgui/releases/tag/v1.70
 
 Breaking Changes:
+
 - ImDrawList: Improved algorithm for mitre joints on thick lines, preserving correct thickness
   up to 90 degrees angles (e.g. rectangles). If you have custom rendering using thick lines,
   they will appear a little thicker now. (#2518) [@rmitton]
@@ -516,6 +534,7 @@ Breaking Changes:
   on them but it is possible you have!).
 
 Other Changes:
+
 - ImDrawList: Added ImDrawCallback_ResetRenderState, a special ImDrawList::AddCallback() value
   to request the renderer back-end to reset its render state. (#2037, #1639, #2452)
   Examples: Added support for ImDrawCallback_ResetRenderState in all renderer back-ends. Each

examples/example_emscripten/Makefile

@@ -1,8 +1,10 @@
 #
 # Makefile to use with emscripten
 # See https://emscripten.org/docs/getting_started/downloads.html
-# for installation instructions. This Makefile assumes you have
+# for installation instructions.
-# loaded emscripten's environment.
+#
+# This Makefile assumes you have loaded emscripten's environment.
+# (On Windows, you may need to execute emsdk_env.bat or encmdprompt.bat ahead)
 #
 # Running `make` will produce three files:
 #  - example_emscripten.html
@@ -13,7 +15,6 @@
 
 CC = emcc
 CXX = em++
-
 EXE = example_emscripten.html
 SOURCES = main.cpp
 SOURCES += ../imgui_impl_sdl.cpp ../imgui_impl_opengl3.cpp
@@ -21,21 +22,41 @@ SOURCES += ../../imgui.cpp ../../imgui_demo.cpp ../../imgui_draw.cpp ../../imgui
 OBJS = $(addsuffix .o, $(basename $(notdir $(SOURCES))))
 UNAME_S := $(shell uname -s)
 
-EMS = -s USE_SDL=2 -s WASM=1
+##---------------------------------------------------------------------
+## EMSCRIPTEN OPTIONS
+##---------------------------------------------------------------------
+
+EMS += -s USE_SDL=2 -s WASM=1
 EMS += -s ALLOW_MEMORY_GROWTH=1
 EMS += -s DISABLE_EXCEPTION_CATCHING=1 -s NO_EXIT_RUNTIME=0
 EMS += -s ASSERTIONS=1
-EMS += -s NO_FILESYSTEM=1 -DIMGUI_DISABLE_FILE_FUNCTIONS
+
-# Uncomment next line to fix possible rendering bugs with emscripten version older then 1.39.0 (https://github.com/ocornut/imgui/issues/2877)
+# Uncomment next line to fix possible rendering bugs with Emscripten version older then 1.39.0 (https://github.com/ocornut/imgui/issues/2877)
 #EMS += -s BINARYEN_TRAP_MODE=clamp
 #EMS += -s SAFE_HEAP=1    ## Adds overhead
 
-CPPFLAGS = -I../ -I../../
+# Emscripten allows preloading a file or folder to be accessible at runtime.
+# The Makefile for this example project suggests embedding the misc/fonts/ folder into our application, it will then be accessible as "/fonts"
+# See documentation for more details: https://emscripten.org/docs/porting/files/packaging_files.html
+# (Default value is 0. Set to 1 to enable file-system and include the misc/fonts/ folder as part of the build.)
+USE_FILE_SYSTEM ?= 0
+ifeq ($(USE_FILE_SYSTEM), 0)
+EMS += -s NO_FILESYSTEM=1 -DIMGUI_DISABLE_FILE_FUNCTIONS
+endif
+ifeq ($(USE_FILE_SYSTEM), 1)
+LDFLAGS += --no-heap-copy --preload-file ../../misc/fonts@/fonts
+endif
+
+##---------------------------------------------------------------------
+## FINAL BUILD FLAGS
+##---------------------------------------------------------------------
+
+CPPFLAGS += -I../ -I../../
 #CPPFLAGS += -g
 CPPFLAGS += -Wall -Wformat -Os
 CPPFLAGS += $(EMS)
-LIBS = $(EMS)
+LIBS += $(EMS)
-LDFLAGS = --shell-file shell_minimal.html
+LDFLAGS += --shell-file shell_minimal.html
 
 ##---------------------------------------------------------------------
 ## BUILD RULES

examples/example_emscripten/main.cpp

@@ -84,13 +84,16 @@ int main(int, char**)
     // - The fonts will be rasterized at a given size (w/ oversampling) and stored into a texture when calling ImFontAtlas::Build()/GetTexDataAsXXXX(), which ImGui_ImplXXXX_NewFrame below will call.
     // - Read 'docs/FONTS.txt' for more instructions and details.
     // - Remember that in C/C++ if you want to include a backslash \ in a string literal you need to write a double backslash \\ !
+    // - Emscripten allows preloading a file or folder to be accessible at runtime. See Makefile for details.
     //io.Fonts->AddFontDefault();
-    //io.Fonts->AddFontFromFileTTF("../../misc/fonts/Roboto-Medium.ttf", 16.0f);
+#ifndef IMGUI_DISABLE_FILE_FUNCTIONS
-    //io.Fonts->AddFontFromFileTTF("../../misc/fonts/Cousine-Regular.ttf", 15.0f);
+    io.Fonts->AddFontFromFileTTF("fonts/Roboto-Medium.ttf", 16.0f);
-    //io.Fonts->AddFontFromFileTTF("../../misc/fonts/DroidSans.ttf", 16.0f);
+    //io.Fonts->AddFontFromFileTTF("fonts/Cousine-Regular.ttf", 15.0f);
-    //io.Fonts->AddFontFromFileTTF("../../misc/fonts/ProggyTiny.ttf", 10.0f);
+    //io.Fonts->AddFontFromFileTTF("fonts/DroidSans.ttf", 16.0f);
-    //ImFont* font = io.Fonts->AddFontFromFileTTF("c:\\Windows\\Fonts\\ArialUni.ttf", 18.0f, NULL, io.Fonts->GetGlyphRangesJapanese());
+    //io.Fonts->AddFontFromFileTTF("fonts/ProggyTiny.ttf", 10.0f);
+    //ImFont* font = io.Fonts->AddFontFromFileTTF("fonts/ArialUni.ttf", 18.0f, NULL, io.Fonts->GetGlyphRangesJapanese());
     //IM_ASSERT(font != NULL);
+#endif
 
     // This function call won't return, and will engage in an infinite loop, processing events from the browser, and dispatching them.
     emscripten_set_main_loop_arg(main_loop, NULL, 0, true);

imgui.cpp

@@ -3992,7 +3992,7 @@ void ImGui::NewFrame()
         window->Active = false;
         window->WriteAccessed = false;
 
-        // Garbage collect (this is totally functional but we may need decide if the side-effects are desirable)
+        // Garbage collect transient buffers of recently unused windows
         if (!window->WasActive && !window->MemoryCompacted && window->LastTimeActive < memory_compact_start_time)
             GcCompactTransientWindowBuffers(window);
     }
@@ -4138,7 +4138,7 @@ void ImGui::Shutdown(ImGuiContext* context)
         IM_DELETE(g.Windows[i]);
     g.Windows.clear();
     g.WindowsFocusOrder.clear();
-    g.WindowsSortBuffer.clear();
+    g.WindowsTempSortBuffer.clear();
     g.CurrentWindow = NULL;
     g.CurrentWindowStack.clear();
     g.WindowsById.Clear();
@@ -4445,19 +4445,19 @@ void ImGui::EndFrame()
 
     // Sort the window list so that all child windows are after their parent
     // We cannot do that on FocusWindow() because childs may not exist yet
-    g.WindowsSortBuffer.resize(0);
+    g.WindowsTempSortBuffer.resize(0);
-    g.WindowsSortBuffer.reserve(g.Windows.Size);
+    g.WindowsTempSortBuffer.reserve(g.Windows.Size);
     for (int i = 0; i != g.Windows.Size; i++)
     {
         ImGuiWindow* window = g.Windows[i];
         if (window->Active && (window->Flags & ImGuiWindowFlags_ChildWindow))       // if a child is active its parent will add it
             continue;
-        AddWindowToSortBuffer(&g.WindowsSortBuffer, window);
+        AddWindowToSortBuffer(&g.WindowsTempSortBuffer, window);
     }
 
     // This usually assert if there is a mismatch between the ImGuiWindowFlags_ChildWindow / ParentWindow values and DC.ChildWindows[] in parents, aka we've done something wrong.
-    IM_ASSERT(g.Windows.Size == g.WindowsSortBuffer.Size);
+    IM_ASSERT(g.Windows.Size == g.WindowsTempSortBuffer.Size);
-    g.Windows.swap(g.WindowsSortBuffer);
+    g.Windows.swap(g.WindowsTempSortBuffer);
     g.IO.MetricsActiveWindows = g.WindowsActiveCount;
 
     // Unlock font atlas
@@ -5883,6 +5883,10 @@ bool ImGui::Begin(const char* name, bool* p_open, ImGuiWindowFlags flags)
     if (window_just_appearing_after_hidden_for_resize && !(flags & ImGuiWindowFlags_ChildWindow))
         window->NavLastIds[0] = 0;
 
+    // Update ->RootWindow and others pointers (before any possible call to FocusWindow)
+    if (first_begin_of_the_frame)
+        UpdateWindowParentAndRootLinks(window, flags, parent_window);
+
     // Process SetNextWindow***() calls
     bool window_pos_set_by_api = false;
     bool window_size_x_set_by_api = false, window_size_y_set_by_api = false;
@@ -5926,8 +5930,6 @@ bool ImGui::Begin(const char* name, bool* p_open, ImGuiWindowFlags flags)
     {
         // Initialize
         const bool window_is_child_tooltip = (flags & ImGuiWindowFlags_ChildWindow) && (flags & ImGuiWindowFlags_Tooltip); // FIXME-WIP: Undocumented behavior of Child+Tooltip for pinned tooltip (#1345)
-        UpdateWindowParentAndRootLinks(window, flags, parent_window);
-
         window->Active = true;
         window->HasCloseButton = (p_open != NULL);
         window->ClipRect = ImVec4(-FLT_MAX,-FLT_MAX,+FLT_MAX,+FLT_MAX);
@@ -6714,18 +6716,19 @@ void ImGui::FocusWindow(ImGuiWindow* window)
         window->DockNode->TabBar->SelectedTabId = window->DockNode->TabBar->NextSelectedTabId = window->ID;
 
     // Move the root window to the top of the pile
-    if (window->RootWindow)
+    IM_ASSERT(window->RootWindow != NULL);
-        window = window->RootWindow;
+    ImGuiWindow* focus_front_window = window->RootWindow; // NB: In docking branch this is window->RootWindowDockStop
+    ImGuiWindow* display_front_window = window->RootWindow;
 
     // Steal focus on active widgets
-    if (window->Flags & ImGuiWindowFlags_Popup) // FIXME: This statement should be unnecessary. Need further testing before removing it..
+    if (focus_front_window->Flags & ImGuiWindowFlags_Popup) // FIXME: This statement may be unnecessary? Need further testing before removing it..
-        if (g.ActiveId != 0 && g.ActiveIdWindow && g.ActiveIdWindow->RootWindow != window)
+        if (g.ActiveId != 0 && g.ActiveIdWindow && g.ActiveIdWindow->RootWindow != focus_front_window)
             ClearActiveID();
 
     // Bring to front
-    BringWindowToFocusFront(window);
+    BringWindowToFocusFront(focus_front_window);
-    if (!(window->Flags & ImGuiWindowFlags_NoBringToFrontOnFocus))
+    if (((window->Flags | display_front_window->Flags) & ImGuiWindowFlags_NoBringToFrontOnFocus) == 0)
-        BringWindowToDisplayFront(window);
+        BringWindowToDisplayFront(display_front_window);
 }
 
 void ImGui::FocusTopMostWindowUnderOne(ImGuiWindow* under_this_window, ImGuiWindow* ignore_window)
@@ -8580,7 +8583,7 @@ ImVec2 ImGui::FindBestWindowPosForPopup(ImGuiWindow* window)
 // [SECTION] KEYBOARD/GAMEPAD NAVIGATION
 //-----------------------------------------------------------------------------
 
-// FIXME-NAV: The existance of SetNavID vs SetNavIDWithRectRel vs SetFocusID is incredibly messy and confusing,
+// FIXME-NAV: The existence of SetNavID vs SetNavIDWithRectRel vs SetFocusID is incredibly messy and confusing,
 // and needs some explanation or serious refactoring.
 void ImGui::SetNavID(ImGuiID id, int nav_layer, ImGuiID focus_scope_id)
 {
@@ -9057,7 +9060,8 @@ static void ImGui::NavUpdate()
     if (g.NavScoringCount > 0) IMGUI_DEBUG_LOG("NavScoringCount %d for '%s' layer %d (Init:%d, Move:%d)\n", g.FrameCount, g.NavScoringCount, g.NavWindow ? g.NavWindow->Name : "NULL", g.NavLayer, g.NavInitRequest || g.NavInitResultId != 0, g.NavMoveRequest);
 #endif
 
-    // Set input source as Gamepad when buttons are pressed before we map Keyboard (some features differs when used with Gamepad vs Keyboard)
+    // Set input source as Gamepad when buttons are pressed (as some features differs when used with Gamepad vs Keyboard)
+    // (do it before we map Keyboard input!)
     bool nav_keyboard_active = (g.IO.ConfigFlags & ImGuiConfigFlags_NavEnableKeyboard) != 0;
     bool nav_gamepad_active = (g.IO.ConfigFlags & ImGuiConfigFlags_NavEnableGamepad) != 0 && (g.IO.BackendFlags & ImGuiBackendFlags_HasGamepad) != 0;
     if (nav_gamepad_active)
@@ -9528,7 +9532,7 @@ static void ImGui::NavUpdateWindowing()
     if (start_windowing_with_gamepad || start_windowing_with_keyboard)
         if (ImGuiWindow* window = g.NavWindow ? g.NavWindow : FindWindowNavFocusable(g.WindowsFocusOrder.Size - 1, -INT_MAX, -1))
         {
-            g.NavWindowingTarget = g.NavWindowingTargetAnim = window;
+            g.NavWindowingTarget = g.NavWindowingTargetAnim = window->RootWindow; // FIXME-DOCK: Will need to use RootWindowDockStop
             g.NavWindowingTimer = g.NavWindowingHighlightAlpha = 0.0f;
             g.NavWindowingToggleLayer = start_windowing_with_keyboard ? false : true;
             g.NavInputSource = start_windowing_with_keyboard ? ImGuiInputSource_NavKeyboard : ImGuiInputSource_NavGamepad;
@@ -15319,6 +15323,7 @@ void ImGui::ShowMetricsWindow(bool* p_open)
     };
 
     Funcs::NodeWindows(g.Windows, "Windows");
+    //Funcs::NodeWindows(g.WindowsFocusOrder, "WindowsFocusOrder");
     if (ImGui::TreeNode("Viewport", "Viewports (%d)", g.Viewports.Size))
     {
         ImGui::Indent(ImGui::GetTreeNodeToLabelSpacing());

imgui.h

@@ -2090,8 +2090,11 @@ struct ImDrawList
     IMGUI_API ImDrawList* CloneOutput() const;                                  // Create a clone of the CmdBuffer/IdxBuffer/VtxBuffer.
 
     // Advanced: Channels
-    // - Use to split render into layers. By switching channels to can render out-of-order (e.g. submit foreground primitives before background primitives)
+    // - Use to split render into layers. By switching channels to can render out-of-order (e.g. submit FG primitives before BG primitives)
-    // - Use to minimize draw calls (e.g. if going back-and-forth between multiple non-overlapping clipping rectangles, prefer to append into separate channels then merge at the end)
+    // - Use to minimize draw calls (e.g. if going back-and-forth between multiple clipping rectangles, prefer to append into separate channels then merge at the end)
+    // - FIXME-OBSOLETE: This API shouldn't have been in ImDrawList in the first place!
+    //   Prefer using your own persistent copy of ImDrawListSplitter as you can stack them.
+    //   Using the ImDrawList::ChannelsXXXX you cannot stack a split over another.
     inline void     ChannelsSplit(int count)    { _Splitter.Split(this, count); }
     inline void     ChannelsMerge()             { _Splitter.Merge(this); }
     inline void     ChannelsSetCurrent(int n)   { _Splitter.SetCurrentChannel(this, n); }

imgui_demo.cpp

@@ -1848,7 +1848,7 @@ static void ShowDemoWindowLayout()
         // Child 1: no border, enable horizontal scrollbar
         {
             ImGuiWindowFlags window_flags = ImGuiWindowFlags_HorizontalScrollbar | (disable_mouse_wheel ? ImGuiWindowFlags_NoScrollWithMouse : 0);
-            ImGui::BeginChild("Child1", ImVec2(ImGui::GetWindowContentRegionWidth() * 0.5f, 260), false, window_flags);
+            ImGui::BeginChild("ChildL", ImVec2(ImGui::GetWindowContentRegionWidth() * 0.5f, 260), false, window_flags);
             for (int i = 0; i < 100; i++)
             {
                 ImGui::Text("%04d: scrollable region", i);
@@ -1866,7 +1866,7 @@ static void ShowDemoWindowLayout()
         {
             ImGuiWindowFlags window_flags = (disable_mouse_wheel ? ImGuiWindowFlags_NoScrollWithMouse : 0) | (disable_menu ? 0 : ImGuiWindowFlags_MenuBar);
             ImGui::PushStyleVar(ImGuiStyleVar_ChildRounding, 5.0f);
-            ImGui::BeginChild("Child2", ImVec2(0, 260), true, window_flags);
+            ImGui::BeginChild("ChildR", ImVec2(0, 260), true, window_flags);
             if (!disable_menu && ImGui::BeginMenuBar())
             {
                 if (ImGui::BeginMenu("Menu"))
@@ -1899,7 +1899,7 @@ static void ShowDemoWindowLayout()
         {
             ImGui::SetCursorPosX(ImGui::GetCursorPosX() + 10);
             ImGui::PushStyleColor(ImGuiCol_ChildBg, IM_COL32(255, 0, 0, 100));
-            ImGui::BeginChild("blah", ImVec2(200, 100), true, ImGuiWindowFlags_None);
+            ImGui::BeginChild("Red", ImVec2(200, 100), true, ImGuiWindowFlags_None);
             for (int n = 0; n < 50; n++)
                 ImGui::Text("Some test %d", n);
             ImGui::EndChild();

imgui_draw.cpp

@@ -1313,7 +1313,7 @@ void ImDrawListSplitter::ClearFreeMemory()
 
 void ImDrawListSplitter::Split(ImDrawList* draw_list, int channels_count)
 {
-    IM_ASSERT(_Current == 0 && _Count <= 1);
+    IM_ASSERT(_Current == 0 && _Count <= 1 && "Nested channel splitting is not supported. Please use separate instances of ImDrawListSplitter.");
     int old_channels_count = _Channels.Size;
     if (old_channels_count < channels_count)
         _Channels.resize(channels_count);

imgui_internal.h

@@ -281,9 +281,6 @@ static inline ImVec4 operator*(const ImVec4& lhs, const ImVec4& rhs)
 #endif
 
 // Helpers: File System
-#if defined(__EMSCRIPTEN__) && !defined(IMGUI_DISABLE_FILE_FUNCTIONS)
-#define IMGUI_DISABLE_FILE_FUNCTIONS
-#endif
 #ifdef IMGUI_DISABLE_FILE_FUNCTIONS
 #define IMGUI_DISABLE_DEFAULT_FILE_FUNCTIONS
 typedef void* ImFileHandle;
@@ -862,6 +859,7 @@ struct ImGuiColumns
     ImRect              HostClipRect;           // Backup of ClipRect at the time of BeginColumns()
     ImRect              HostWorkRect;           // Backup of WorkRect at the time of BeginColumns()
     ImVector<ImGuiColumnData> Columns;
+    ImDrawListSplitter  Splitter;
 
     ImGuiColumns()      { Clear(); }
     void Clear()
@@ -1159,8 +1157,8 @@ struct ImGuiContext
 
     // Windows state
     ImVector<ImGuiWindow*>  Windows;                            // Windows, sorted in display order, back to front
-    ImVector<ImGuiWindow*>  WindowsFocusOrder;                  // Windows, sorted in focus order, back to front
+    ImVector<ImGuiWindow*>  WindowsFocusOrder;                  // Windows, sorted in focus order, back to front. (FIXME: We could only store root windows here! Need to sort out the Docking equivalent which is RootWindowDockStop and is unfortunately a little more dynamic)
-    ImVector<ImGuiWindow*>  WindowsSortBuffer;
+    ImVector<ImGuiWindow*>  WindowsTempSortBuffer;              // Temporary buffer used in EndFrame() to reorder windows so parents are kept before their child
     ImVector<ImGuiWindow*>  CurrentWindowStack;
     ImGuiStorage            WindowsById;                        // Map window's ImGuiID to ImGuiWindow*
     int                     WindowsActiveCount;                 // Number of unique windows submitted by frame
@@ -1430,7 +1428,7 @@ struct ImGuiContext
         NavInitResultId = 0;
         NavMoveFromClampedRefRect = false;
         NavMoveRequest = false;
-        NavMoveRequestFlags = 0;
+        NavMoveRequestFlags = ImGuiNavMoveFlags_None;
         NavMoveRequestForward = ImGuiNavForward_None;
         NavMoveDir = NavMoveDirLast = NavMoveClipDir = ImGuiDir_None;
 
@@ -1447,11 +1445,11 @@ struct ImGuiContext
         MouseCursor = ImGuiMouseCursor_Arrow;
 
         DragDropActive = DragDropWithinSourceOrTarget = false;
-        DragDropSourceFlags = 0;
+        DragDropSourceFlags = ImGuiDragDropFlags_None;
         DragDropSourceFrameCount = -1;
         DragDropMouseButton = -1;
         DragDropTargetId = 0;
-        DragDropAcceptFlags = 0;
+        DragDropAcceptFlags = ImGuiDragDropFlags_None;
         DragDropAcceptIdCurrRectSurface = 0.0f;
         DragDropAcceptIdPrev = DragDropAcceptIdCurr = 0;
         DragDropAcceptFrameCount = -1;
@@ -1568,7 +1566,7 @@ struct IMGUI_API ImGuiWindowTempData
         GroupOffset = ImVec1(0.0f);
 
         LastItemId = 0;
-        LastItemStatusFlags = 0;
+        LastItemStatusFlags = ImGuiItemStatusFlags_None;
         LastItemRect = LastItemDisplayRect = ImRect();
 
         NavLayerActiveMask = NavLayerActiveMaskNext = 0x00;
@@ -1597,7 +1595,7 @@ struct IMGUI_API ImGuiWindowTempData
 // Storage for one window
 struct IMGUI_API ImGuiWindow
 {
-    char*                   Name;
+    char*                   Name;                               // Window name, owned by the window.
     ImGuiID                 ID;                                 // == ImHashStr(Name)
     ImGuiWindowFlags        Flags, FlagsPreviousFrame;          // See enum ImGuiWindowFlags_
     ImGuiWindowClass        WindowClass;                        // Advanced users only. Set with SetNextWindowClass()
@@ -1768,7 +1766,7 @@ struct ImGuiTabItem
     float               Width;                  // Width currently displayed
     float               ContentWidth;           // Width of actual contents, stored during BeginTabItem() call
 
-    ImGuiTabItem()      { ID = 0; Flags = 0; Window = NULL; LastFrameVisible = LastFrameSelected = -1; NameOffset = -1; Offset = Width = ContentWidth = 0.0f; }
+    ImGuiTabItem()      { ID = 0; Flags = ImGuiTabItemFlags_None; Window = NULL; LastFrameVisible = LastFrameSelected = -1; NameOffset = -1; Offset = Width = ContentWidth = 0.0f; }
 };
 
 // Storage for a tab bar (sizeof() 92~96 bytes)
@@ -1817,6 +1815,7 @@ struct ImGuiTabBar
 
 namespace ImGui
 {
+    // Windows
     // We should always have a CurrentWindow in the stack (there is an implicit "Debug" window)
     // If this ever crash because g.CurrentWindow is NULL it means that either
     // - ImGui::NewFrame() has never been called, which is illegal.
@@ -1825,11 +1824,6 @@ namespace ImGui
     inline    ImGuiWindow*  GetCurrentWindow()          { ImGuiContext& g = *GImGui; g.CurrentWindow->WriteAccessed = true; return g.CurrentWindow; }
     IMGUI_API ImGuiWindow*  FindWindowByID(ImGuiID id);
     IMGUI_API ImGuiWindow*  FindWindowByName(const char* name);
-    IMGUI_API void          FocusWindow(ImGuiWindow* window);
-    IMGUI_API void          FocusTopMostWindowUnderOne(ImGuiWindow* under_this_window, ImGuiWindow* ignore_window);
-    IMGUI_API void          BringWindowToFocusFront(ImGuiWindow* window);
-    IMGUI_API void          BringWindowToDisplayFront(ImGuiWindow* window);
-    IMGUI_API void          BringWindowToDisplayBack(ImGuiWindow* window);
     IMGUI_API void          UpdateWindowParentAndRootLinks(ImGuiWindow* window, ImGuiWindowFlags flags, ImGuiWindow* parent_window);
     IMGUI_API ImVec2        CalcWindowExpectedSize(ImGuiWindow* window);
     IMGUI_API bool          IsWindowChildOf(ImGuiWindow* window, ImGuiWindow* potential_parent);
@@ -1838,9 +1832,15 @@ namespace ImGui
     IMGUI_API void          SetWindowPos(ImGuiWindow* window, const ImVec2& pos, ImGuiCond cond = 0);
     IMGUI_API void          SetWindowSize(ImGuiWindow* window, const ImVec2& size, ImGuiCond cond = 0);
     IMGUI_API void          SetWindowCollapsed(ImGuiWindow* window, bool collapsed, ImGuiCond cond = 0);
-    IMGUI_API void          GcCompactTransientWindowBuffers(ImGuiWindow* window);
-    IMGUI_API void          GcAwakeTransientWindowBuffers(ImGuiWindow* window);
 
+    // Windows: Display Order and Focus Order
+    IMGUI_API void          FocusWindow(ImGuiWindow* window);
+    IMGUI_API void          FocusTopMostWindowUnderOne(ImGuiWindow* under_this_window, ImGuiWindow* ignore_window);
+    IMGUI_API void          BringWindowToFocusFront(ImGuiWindow* window);
+    IMGUI_API void          BringWindowToDisplayFront(ImGuiWindow* window);
+    IMGUI_API void          BringWindowToDisplayBack(ImGuiWindow* window);
+    
+    // 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) { return GetForegroundDrawList(window->Viewport); }
@@ -1879,6 +1879,7 @@ namespace ImGui
 
     // Basic Accessors
     inline ImGuiID          GetItemID()     { ImGuiContext& g = *GImGui; return g.CurrentWindow->DC.LastItemId; }
+    inline ImGuiItemStatusFlags GetItemStatusFlags() { ImGuiContext& g = *GImGui; return g.CurrentWindow->DC.LastItemStatusFlags; }
     inline ImGuiID          GetActiveID()   { ImGuiContext& g = *GImGui; return g.ActiveId; }
     inline ImGuiID          GetFocusID()    { ImGuiContext& g = *GImGui; return g.NavId; }
     IMGUI_API void          SetActiveID(ImGuiID id, ImGuiWindow* window);
@@ -1887,7 +1888,7 @@ namespace ImGui
     IMGUI_API ImGuiID       GetHoveredID();
     IMGUI_API void          SetHoveredID(ImGuiID id);
     IMGUI_API void          KeepAliveID(ImGuiID id);
-    IMGUI_API void          MarkItemEdited(ImGuiID id);
+    IMGUI_API void          MarkItemEdited(ImGuiID id);     // Mark data associated to given item as "edited", used by IsItemDeactivatedAfterEdit() function.
     IMGUI_API void          PushOverrideID(ImGuiID id);     // Push given value at the top of the ID stack (whereas PushID combines old and new hashes)
 
     // Basic Helpers for widget code
@@ -2000,7 +2001,7 @@ namespace ImGui
     IMGUI_API void          ClearDragDrop();
     IMGUI_API bool          IsDragDropPayloadBeingAccepted();
 
-    // New Columns API (FIXME-WIP)
+    // Internal Columns API (this is not exposed because we will encourage transitioning to the Tables api)
     IMGUI_API void          BeginColumns(const char* str_id, int count, ImGuiColumnsFlags flags = 0); // setup number of columns. use an identifier to distinguish multiple column sets. close with EndColumns().
     IMGUI_API void          EndColumns();                                                             // close columns
     IMGUI_API void          PushColumnClipRect(int column_index);
@@ -2108,6 +2109,10 @@ namespace ImGui
     IMGUI_API void          ShadeVertsLinearColorGradientKeepAlpha(ImDrawList* draw_list, int vert_start_idx, int vert_end_idx, ImVec2 gradient_p0, ImVec2 gradient_p1, ImU32 col0, ImU32 col1);
     IMGUI_API void          ShadeVertsLinearUV(ImDrawList* draw_list, int vert_start_idx, int vert_end_idx, const ImVec2& a, const ImVec2& b, const ImVec2& uv_a, const ImVec2& uv_b, bool clamp);
 
+    // Garbage collection
+    IMGUI_API void          GcCompactTransientWindowBuffers(ImGuiWindow* window);
+    IMGUI_API void          GcAwakeTransientWindowBuffers(ImGuiWindow* window);
+
     // Debug Tools
     inline void             DebugDrawItemRect(ImU32 col = IM_COL32(255,0,0,255))    { ImGuiContext& g = *GImGui; ImGuiWindow* window = g.CurrentWindow; GetForegroundDrawList(window)->AddRect(window->DC.LastItemRect.Min, window->DC.LastItemRect.Max, col); }
     inline void             DebugStartItemPicker()                                  { ImGuiContext& g = *GImGui; g.DebugItemPickerActive = true; }

imgui_widgets.cpp

@@ -3465,14 +3465,23 @@ bool ImGui::InputTextEx(const char* label, const char* hint, char* buf, int buf_
             EndGroup();
             return false;
         }
-        if (!BeginChildFrame(id, frame_bb.GetSize()))
+
+        // We reproduce the contents of BeginChildFrame() in order to provide 'label' so our window internal data are easier to read/debug.
+        PushStyleColor(ImGuiCol_ChildBg, style.Colors[ImGuiCol_FrameBg]);
+        PushStyleVar(ImGuiStyleVar_ChildRounding, style.FrameRounding);
+        PushStyleVar(ImGuiStyleVar_ChildBorderSize, style.FrameBorderSize);
+        PushStyleVar(ImGuiStyleVar_WindowPadding, style.FramePadding);
+        bool child_visible = BeginChildEx(label, id, frame_bb.GetSize(), true, ImGuiWindowFlags_NoMove | ImGuiWindowFlags_AlwaysUseWindowPadding);
+        PopStyleVar(3);
+        PopStyleColor();
+        if (!child_visible)
         {
-            EndChildFrame();
+            EndChild();
             EndGroup();
             return false;
         }
         draw_window = g.CurrentWindow; // Child window
-        draw_window->DC.NavLayerActiveMaskNext |= draw_window->DC.NavLayerCurrentMask; // This is to ensure that EndChild() will display a navigation highlight
+        draw_window->DC.NavLayerActiveMaskNext |= draw_window->DC.NavLayerCurrentMask; // This is to ensure that EndChild() will display a navigation highlight so we can "enter" into it.
         inner_size.x -= draw_window->ScrollbarSizes.x;
     }
     else
@@ -4161,7 +4170,7 @@ bool ImGui::InputTextEx(const char* label, const char* hint, char* buf, int buf_
     if (is_multiline)
     {
         Dummy(text_size + ImVec2(0.0f, g.FontSize)); // Always add room to scroll an extra line
-        EndChildFrame();
+        EndChild();
         EndGroup();
     }
 
@@ -7519,7 +7528,7 @@ void ImGui::PushColumnsBackground()
     ImGuiColumns* columns = window->DC.CurrentColumns;
     if (columns->Count == 1)
         return;
-    window->DrawList->ChannelsSetCurrent(0);
+    columns->Splitter.SetCurrentChannel(window->DrawList, 0);
     int cmd_size = window->DrawList->CmdBuffer.Size;
     PushClipRect(columns->HostClipRect.Min, columns->HostClipRect.Max, false);
     IM_UNUSED(cmd_size);
@@ -7532,7 +7541,7 @@ void ImGui::PopColumnsBackground()
     ImGuiColumns* columns = window->DC.CurrentColumns;
     if (columns->Count == 1)
         return;
-    window->DrawList->ChannelsSetCurrent(columns->Current + 1);
+    columns->Splitter.SetCurrentChannel(window->DrawList, columns->Current + 1);
     PopClipRect();
 }
 
@@ -7623,8 +7632,8 @@ void ImGui::BeginColumns(const char* str_id, int columns_count, ImGuiColumnsFlag
 
     if (columns->Count > 1)
     {
-        window->DrawList->ChannelsSplit(1 + columns->Count);
+        columns->Splitter.Split(window->DrawList, 1 + columns->Count);
-        window->DrawList->ChannelsSetCurrent(1);
+        columns->Splitter.SetCurrentChannel(window->DrawList, 1);
         PushColumnClipRect(0);
     }
 
@@ -7663,14 +7672,14 @@ void ImGui::NextColumn()
         // Columns 1+ ignore IndentX (by canceling it out)
         // FIXME-COLUMNS: Unnecessary, could be locked?
         window->DC.ColumnsOffset.x = GetColumnOffset(columns->Current) - window->DC.Indent.x + column_padding;
-        window->DrawList->ChannelsSetCurrent(columns->Current + 1);
+        columns->Splitter.SetCurrentChannel(window->DrawList, columns->Current + 1);
     }
     else
     {
         // New row/line
         // Column 0 honor IndentX
         window->DC.ColumnsOffset.x = ImMax(column_padding - window->WindowPadding.x, 0.0f);
-        window->DrawList->ChannelsSetCurrent(1);
+        columns->Splitter.SetCurrentChannel(window->DrawList, 1);
         columns->Current = 0;
         columns->LineMinY = columns->LineMaxY;
     }
@@ -7700,7 +7709,7 @@ void ImGui::EndColumns()
     if (columns->Count > 1)
     {
         PopClipRect();
-        window->DrawList->ChannelsMerge();
+        columns->Splitter.Merge(window->DrawList);
     }
 
     const ImGuiColumnsFlags flags = columns->Flags;