Docking: Fix appending to windows causing a child window to be insert…

…ed to g.WindowsFocusOrder which eventually causes a crash. (ocornut#5515)

docs/CHANGELOG.txt

@@ -70,6 +70,7 @@ Other Changes:
 - Backends: Metal: Use __bridge for ARC based systems. (#5403) [@stack]
 - Backends: Metal: Add dispatch synchronization. (#5447) [@luigifcruz]
 - Backends: OSX: Fixes to support full app creation in C++. (#5403) [@stack]
+- Window: Fixed a potential crash when appending to a child window. [@rokups] (#5515)
 
 
 -----------------------------------------------------------------------

imgui.cpp

@@ -5474,7 +5474,6 @@ static ImGuiWindow* CreateNewWindow(const char* name, ImGuiWindowFlags flags)
         g.Windows.push_front(window); // Quite slow but rare and only once
     else
         g.Windows.push_back(window);
-    UpdateWindowInFocusOrderList(window, true, window->Flags);
 
     return window;
 }
@@ -6087,8 +6086,6 @@ bool ImGui::Begin(const char* name, bool* p_open, ImGuiWindowFlags flags)
     const bool window_just_created = (window == NULL);
     if (window_just_created)
         window = CreateNewWindow(name, flags);
-    else
-        UpdateWindowInFocusOrderList(window, window_just_created, flags);
 
     // Automatically disable manual moving/resizing when NoInputs is set
     if ((flags & ImGuiWindowFlags_NoInputs) == ImGuiWindowFlags_NoInputs)
@@ -6116,6 +6113,7 @@ bool ImGui::Begin(const char* name, bool* p_open, ImGuiWindowFlags flags)
     // Update Flags, LastFrameActive, BeginOrderXXX fields
     if (first_begin_of_the_frame)
     {
+        UpdateWindowInFocusOrderList(window, window_just_created, flags);
         window->Flags = (ImGuiWindowFlags)flags;
         window->LastFrameActive = current_frame;
         window->LastTimeActive = (float)g.Time;