Added IO::WantRender bool to facilitate lazy rendering support.

imgui.cpp

@@ -4176,6 +4176,7 @@ void ImGui::UpdateMouseWheel()
     ImGuiWindow* window = g.WheelingWindow ? g.WheelingWindow : g.HoveredWindow;
     if (!window || window->Collapsed)
         return;
+    g.IO.WantRender = true;
 
     // Zoom / Scale window
     // FIXME-OBSOLETE: This is an old feature, it still works but pretty much nobody is using it and may be best redesigned.
@@ -4345,6 +4346,7 @@ void ImGui::NewFrame()
 
     // Load settings on first frame, save settings when modified (after a delay)
     UpdateSettings();
+    g.IO.WantRender = false;
 
     g.Time += g.IO.DeltaTime;
     g.WithinFrameScope = true;
@@ -4402,6 +4404,8 @@ void ImGui::NewFrame()
         g.HoveredIdTimer += g.IO.DeltaTime;
     if (g.HoveredId && g.ActiveId != g.HoveredId)
         g.HoveredIdNotActiveTimer += g.IO.DeltaTime;
+    if (g.HoveredId != g.HoveredIdPreviousFrame)
+        g.IO.WantRender = true;
     g.HoveredIdPreviousFrame = g.HoveredId;
     g.HoveredIdPreviousFrameUsingMouseWheel = g.HoveredIdUsingMouseWheel;
     g.HoveredId = 0;
@@ -4420,7 +4424,10 @@ void ImGui::NewFrame()
 
     // Update ActiveId data (clear reference to active widget if the widget isn't alive anymore)
     if (g.ActiveId)
+    {
         g.ActiveIdTimer += g.IO.DeltaTime;
+        g.IO.WantRender = true;
+    }
     g.LastActiveIdTimer += g.IO.DeltaTime;
     g.ActiveIdPreviousFrame = g.ActiveId;
     g.ActiveIdPreviousFrameWindow = g.ActiveIdWindow;
@@ -4490,7 +4497,11 @@ void ImGui::NewFrame()
 
     // Background darkening/whitening
     if (GetTopMostPopupModal() != NULL || (g.NavWindowingTarget != NULL && g.NavWindowingHighlightAlpha > 0.0f))
+    {
         g.DimBgRatio = ImMin(g.DimBgRatio + g.IO.DeltaTime * 6.0f, 1.0f);
+        if (g.DimBgRatio != 1.0)
+            g.IO.WantRender = true;
+    }
     else
         g.DimBgRatio = ImMax(g.DimBgRatio - g.IO.DeltaTime * 10.0f, 0.0f);
 
@@ -6905,6 +6916,7 @@ void ImGui::FocusWindow(ImGuiWindow* window)
     BringWindowToFocusFront(focus_front_window);
     if (((window->Flags | display_front_window->Flags) & ImGuiWindowFlags_NoBringToFrontOnFocus) == 0)
         BringWindowToDisplayFront(display_front_window);
+    g.IO.WantRender = true;
 }
 
 void ImGui::FocusTopMostWindowUnderOne(ImGuiWindow* under_this_window, ImGuiWindow* ignore_window)

imgui.h

@@ -1976,6 +1976,7 @@ struct ImGuiIO
     // (when reading from the io.WantCaptureMouse, io.WantCaptureKeyboard flags to dispatch your inputs, it is
     //  generally easier and more correct to use their state BEFORE calling NewFrame(). See FAQ for details!)
     //------------------------------------------------------------------
+    bool        WantRender;                         // When io.WantRender is true imgui is processing animation or other state changes which will require a redraw.
 
     bool        WantCaptureMouse;                   // Set when Dear ImGui will use mouse inputs, in this case do not dispatch them to your main game/application (either way, always pass on mouse inputs to imgui). (e.g. unclicked mouse is hovering over an imgui window, widget is active, mouse was clicked over an imgui window, etc.).
     bool        WantCaptureKeyboard;                // Set when Dear ImGui will use keyboard inputs, in this case do not dispatch them to your main game/application (either way, always pass keyboard inputs to imgui). (e.g. InputText active, or an imgui window is focused and navigation is enabled, etc.).

imgui_widgets.cpp

@@ -6119,6 +6119,7 @@ bool ImGui::TreeNodeBehavior(ImGuiID id, ImGuiTreeNodeFlags flags, const char* l
 
         if (toggled)
         {
+            g.IO.WantRender = true;
             is_open = !is_open;
             window->DC.StateStorage->SetInt(id, is_open);
             g.LastItemData.StatusFlags |= ImGuiItemStatusFlags_ToggledOpen;