Menus: Fix sub-menu inhibition stopping working in some cases. (Amend WIP) (#2517, #5614, noticed in #5546)

Amend bda2cde6
Fixes the case where following menu hover sequence results in incorrect RestoreNavWindow (previously SourceWindow) pointing to opened sub-menu:
1. Hover "Menu -> Options" - Open ##Menu_01 window
2. Hover "Menu -> Colors"  - SourceWindow incorrectly points to ##Menu_01 window

docs/CHANGELOG.txt

@@ -79,6 +79,9 @@ Other Changes:
 - Window: Fixed a potential crash when appending to a child window. (#5515, #3496, #4797) [@rokups]
 - IO: Added ImGuiKey_MouseXXX aliases for mouse buttons/wheel so all operations done on ImGuiKey
   can apply to mouse data as well. (#4921)
+- Menus: Fixed incorrect sub-menu parent association when opening a menu by closing another.
+  Among other things, it would accidentally break part of the closing heuristic logic when moving
+  towards a sub-menu. (#2517, #5614). [@rokups]
 - Nav: Fixed moving/resizing window with gamepad or keyboard when running at very high framerate.
 - Nav: Pressing Space/GamepadFaceDown on a repeating button uses the same repeating rate as a mouse hold.
 - Platform IME: [Windows] Removed call to ImmAssociateContextEx() leading to freeze on some setups.

imgui.cpp

@@ -9336,7 +9336,7 @@ void ImGui::OpenPopupEx(ImGuiID id, ImGuiPopupFlags popup_flags)
     ImGuiPopupData popup_ref; // Tagged as new ref as Window will be set back to NULL if we write this into OpenPopupStack.
     popup_ref.PopupId = id;
     popup_ref.Window = NULL;
-    popup_ref.SourceWindow = g.NavWindow;
+    popup_ref.BackupNavWindow = g.NavWindow;            // When popup closes focus may be restored to NavWindow (depend on window type).
     popup_ref.OpenFrameCount = g.FrameCount;
     popup_ref.OpenParentId = parent_window->IDStack.back();
     popup_ref.OpenPopupPos = NavCalcPreferredRefPos();
@@ -9438,12 +9438,13 @@ void ImGui::ClosePopupToLevel(int remaining, bool restore_focus_to_window_under_
     IM_ASSERT(remaining >= 0 && remaining < g.OpenPopupStack.Size);
 
     // Trim open popup stack
-    ImGuiWindow* focus_window = g.OpenPopupStack[remaining].SourceWindow;
     ImGuiWindow* popup_window = g.OpenPopupStack[remaining].Window;
+    ImGuiWindow* popup_backup_nav_window = g.OpenPopupStack[remaining].BackupNavWindow;
     g.OpenPopupStack.resize(remaining);
 
     if (restore_focus_to_window_under_popup)
     {
+        ImGuiWindow* focus_window = (popup_window && popup_window->Flags & ImGuiWindowFlags_ChildMenu) ? popup_window->ParentWindow : popup_backup_nav_window;
         if (focus_window && !focus_window->WasActive && popup_window)
         {
             // Fallback
@@ -12689,8 +12690,12 @@ void ImGui::ShowMetricsWindow(bool* p_open)
     {
         for (int i = 0; i < g.OpenPopupStack.Size; i++)
         {
-            ImGuiWindow* window = g.OpenPopupStack[i].Window;
+            // As it's difficult to interact with tree nodes while popups are open, we display everything inline.
-            BulletText("PopupID: %08x, Window: '%s'%s%s", g.OpenPopupStack[i].PopupId, window ? window->Name : "NULL", window && (window->Flags & ImGuiWindowFlags_ChildWindow) ? " ChildWindow" : "", window && (window->Flags & ImGuiWindowFlags_ChildMenu) ? " ChildMenu" : "");
+            const ImGuiPopupData* popup_data = &g.OpenPopupStack[i];
+            ImGuiWindow* window = popup_data->Window;
+            BulletText("PopupID: %08x, Window: '%s' (%s%s), BackupNavWindow '%s', ParentWindow '%s'",
+                popup_data->PopupId, window ? window->Name : "NULL", window && (window->Flags & ImGuiWindowFlags_ChildWindow) ? "Child;" : "", window && (window->Flags & ImGuiWindowFlags_ChildMenu) ? "Menu;" : "",
+                popup_data->BackupNavWindow ? popup_data->BackupNavWindow->Name : "NULL", window && window->ParentWindow ? window->ParentWindow->Name : "NULL");
         }
         TreePop();
     }

imgui.h

@@ -65,7 +65,7 @@ Index of this file:
 // Version
 // (Integer encoded as XYYZZ for use in #if preprocessor conditionals. Work in progress versions typically starts at XYY99 then bounce up to XYY00, XYY01 etc. when release tagging happens)
 #define IMGUI_VERSION               "1.89 WIP"
-#define IMGUI_VERSION_NUM           18812
+#define IMGUI_VERSION_NUM           18813
 #define IMGUI_CHECKVERSION()        ImGui::DebugCheckVersionAndDataLayout(IMGUI_VERSION, sizeof(ImGuiIO), sizeof(ImGuiStyle), sizeof(ImVec2), sizeof(ImVec4), sizeof(ImDrawVert), sizeof(ImDrawIdx))
 #define IMGUI_HAS_TABLE
 

imgui_internal.h

@@ -1048,7 +1048,7 @@ struct ImGuiPopupData
 {
     ImGuiID             PopupId;        // Set on OpenPopup()
     ImGuiWindow*        Window;         // Resolved on BeginPopup() - may stay unresolved if user never calls OpenPopup()
-    ImGuiWindow*        SourceWindow;   // Set on OpenPopup() copy of NavWindow at the time of opening the popup
+    ImGuiWindow*        BackupNavWindow;// Set on OpenPopup(), a NavWindow that will be restored on popup close
     int                 ParentNavLayer; // Resolved on BeginPopup(). Actually a ImGuiNavLayer type (declared down below), initialized to -1 which is not part of an enum, but serves well-enough as "not any of layers" value
     int                 OpenFrameCount; // Set on OpenPopup()
     ImGuiID             OpenParentId;   // Set on OpenPopup(), we need this to differentiate multiple menu sets from each others (e.g. inside menu bar vs loose menu items)

imgui_widgets.cpp

@@ -7107,7 +7107,8 @@ bool ImGui::BeginMenuEx(const char* label, const char* icon, bool enabled)
         // Close menu when not hovering it anymore unless we are moving roughly in the direction of the menu
         // Implement http://bjk5.com/post/44698559168/breaking-down-amazons-mega-dropdown to avoid using timers, so menus feels more reactive.
         bool moving_toward_child_menu = false;
-        ImGuiWindow* child_menu_window = (g.BeginPopupStack.Size < g.OpenPopupStack.Size && g.OpenPopupStack[g.BeginPopupStack.Size].SourceWindow == window) ? g.OpenPopupStack[g.BeginPopupStack.Size].Window : NULL;
+        ImGuiPopupData* child_popup = (g.BeginPopupStack.Size < g.OpenPopupStack.Size) ? &g.OpenPopupStack[g.BeginPopupStack.Size] : NULL; // Popup candidate (testing below)
+        ImGuiWindow* child_menu_window = (child_popup && child_popup->Window && child_popup->Window->ParentWindow == window) ? child_popup->Window : NULL;
         if (g.HoveredWindow == window && child_menu_window != NULL && !(window->Flags & ImGuiWindowFlags_MenuBar))
         {
             float ref_unit = g.FontSize; // FIXME-DPI