Docking: Fixed one-frame flickering on reappearing windows binding to a dock node where a later-submitted window was already bound.

docs/CHANGELOG.txt

@@ -153,6 +153,8 @@ Docking+Viewports Branch:
 
 - Viewports: Closing a viewport via OS/platform means (e.g. OS close button or task-bar menu),
   mark all windows in this viewport as closed.
+- Docking: Fixed one-frame flickering on reappearing windows binding to a dock node
+  where a later-submitted window was already bound.
 - Docking: Fixed dragging from title-bar empty space (regression from 1.88 related to
   keeping ID alive when calling low-level ButtonBehavior() directly). (#5181, #2645)
 - Docking: [Internal] DockBuilderDockWindow() API calls don't clear docking order

imgui.cpp

@@ -18407,7 +18407,7 @@ void ImGui::BeginDocked(ImGuiWindow* window, bool* p_open)
     {
         if (node->State == ImGuiDockNodeState_HostWindowHiddenBecauseWindowsAreResizing)
             window->DockIsActive = true;
-        if (node->Windows.Size > 1)
+        if (node->Windows.Size > 1 && window->Appearing) // Only hide appearing window
             DockNodeHideWindowDuringHostWindowCreation(window);
         return;
     }