Popups & Modals: Fix (amended) somehow undocumented Popup+Child behavior (useful for e.g. #718, #4461 and probably other things)

(broken by 1c4066cd)

imgui.cpp

@@ -5511,7 +5511,7 @@ static void UpdateWindowInFocusOrderList(ImGuiWindow* window, bool just_created,
 {
     ImGuiContext& g = *GImGui;
 
-    const bool new_is_explicit_child = (new_flags & ImGuiWindowFlags_ChildWindow) != 0;
+    const bool new_is_explicit_child = (new_flags & ImGuiWindowFlags_ChildWindow) != 0 && ((new_flags & ImGuiWindowFlags_Popup) == 0 || (new_flags & ImGuiWindowFlags_ChildMenu) != 0);
     const bool child_flag_changed = new_is_explicit_child != window->IsExplicitChild;
     if ((just_created || child_flag_changed) && !new_is_explicit_child)
     {

imgui.h

@@ -23,7 +23,7 @@
 // Library Version
 // (Integer encoded as XYYZZ for use in #if preprocessor conditionals, e.g. '#if IMGUI_VERSION_NUM > 12345')
 #define IMGUI_VERSION               "1.89 WIP"
-#define IMGUI_VERSION_NUM           18820
+#define IMGUI_VERSION_NUM           18821
 #define IMGUI_HAS_TABLE
 
 /*