Fix Qt6 menus randomly not displaying

lazpaint/lazpaintmainform.pas

@@ -905,9 +905,9 @@   TFMain = class(TForm)
 
 implementation
 
-uses LCLIntf, BGRAUTF8, ugraph, math, umac, uclipboard, ucursors,
-   ufilters, ULoadImage, ULoading, UFileExtensions, UBrushType,
-   ugeometricbrush, UPreviewDialog, UQuestion, BGRALayerOriginal,
+uses LCLIntf, InterfaceBase, LCLPlatformDef, BGRAUTF8, ugraph, math, umac,
+   uclipboard, ucursors, ufilters, ULoadImage, ULoading, UFileExtensions,
+   UBrushType, ugeometricbrush, UPreviewDialog, UQuestion, BGRALayerOriginal,
    BGRATransform, LCVectorPolyShapes, URaw, UFileSystem,
    UTranslation, UPython, BCTypes;
 
@@ -1177,7 +1177,7 @@ procedure TFMain.FormShow(Sender: TObject);
   m: TMainFormMenu;
   startFillControlWidth: LongInt;
   iconSize: Integer;
-  toolbarDPI, w, h: integer;
+  toolbarDPI, w, h, i: integer;
 begin
   if FLayout.Menu = nil then
   begin
@@ -1218,6 +1218,30 @@ procedure TFMain.FormShow(Sender: TObject);
     m.Apply;
     FLayout.Menu := m;
 
+    // Force Qt5/Qt6 to rebuild main menu by detaching and reattaching
+    // This works around menu items randomly not displaying on Qt widgetsets
+    // Qt6 has race conditions during early widget initialization that can
+    // cause menu items to not appear. Multiple ProcessMessages calls and
+    // explicit visibility toggling helps ensure the menu bar is fully built.
+    if WidgetSet.LCLPlatform in [lpQt5, lpQt6] then
+    begin
+      // First pass: detach menu and process
+      Self.Menu := nil;
+      Application.ProcessMessages;
+      Application.ProcessMessages;
+      // Second pass: reattach and force visibility on all top-level menus
+      Self.Menu := MainMenu1;
+      for i := 0 to MainMenu1.Items.Count - 1 do
+      begin
+        MainMenu1.Items[i].Visible := False;
+        MainMenu1.Items[i].Visible := True;
+      end;
+      Application.ProcessMessages;
+      // Force the form to update its menu bar
+      MainMenu1.HandleNeeded;
+      Application.ProcessMessages;
+    end;
+
     SVGImageList1.Width := iconSize;
     SVGImageList1.Height := iconSize;
     SVGImageList1.PopulateImageList(SVGRasterImageList1, [iconSize]);

lazpaint/uimageview.pas

@@ -2,8 +2,10 @@
 unit UImageView;
 
 {$mode objfpc}{$H+}
-{$IF defined(LINUX) and not defined(LCLqt5)}{$DEFINE IMAGEVIEW_DIRECTUPDATE}{$ENDIF}
+{$IF defined(LINUX) and not defined(LCLqt5) and not defined(LCLqt6)}{$DEFINE IMAGEVIEW_DIRECTUPDATE}{$ENDIF}
 {$DEFINE DRAW_TOOL_OUTSIDE_IMAGE}
+// Qt5 needs neither DIRECTUPDATE nor QUICKUPDATE
+// Qt6 needs QUICKUPDATE (forces repaint) but not DIRECTUPDATE (bypasses Qt paint system)
 {$IF not defined(DARWIN) and not defined(LCLqt5)}{$DEFINE IMAGEVIEW_QUICKUPDATE}{$ENDIF}
 
 interface

lazpaint/umenu.pas

@@ -107,6 +107,25 @@ procedure TMainFormMenu.IconSizeItemClick(Sender: TObject);
   FInstance.ChangeIconSize(item.Tag);
 end;
 
+// Helper function to find action by name using direct iteration
+// This works around Qt6 ActionByName issues during early initialization
+function FindActionByNameDirect(AActionList: TActionList; const AName: string): TBasicAction;
+var
+  k: Integer;
+  actName: string;
+begin
+  Result := nil;
+  for k := 0 to AActionList.ActionCount - 1 do
+  begin
+    actName := AActionList.Actions[k].Name;
+    if SameText(actName, AName) then
+    begin
+      Result := AActionList.Actions[k];
+      Exit;
+    end;
+  end;
+end;
+
 procedure TMainFormMenu.AddMenus(AMenu: TMenuItem; AActionList: TActionList;
   AActionsCommaText: string; AIndex: integer);
 var actions: TStringList;
@@ -158,7 +177,7 @@ procedure TMainFormMenu.AddMenus(AMenu: TMenuItem; AActionList: TActionList;
       item.Caption := cLineCaption
     else
     begin
-      foundAction := AActionList.ActionByName(actions[i]);
+      foundAction := FindActionByNameDirect(AActionList, actions[i]);
       if foundAction <> nil then
         item.Action := foundAction
       else
@@ -202,13 +221,13 @@ procedure TMainFormMenu.AddMenus(AMenu: TMenuItem; AActionList: TActionList;
         if Assigned(item) and (actions[i] = 'EditShapeAlign') then
         begin
           item.Caption := rsAlignShape;
-          AddSubItem(AActionList.ActionByName('EditShapeAlignLeft'));
-          AddSubItem(AActionList.ActionByName('EditShapeCenterHorizontally'));
-          AddSubItem(AActionList.ActionByName('EditShapeAlignRight'));
+          AddSubItem(FindActionByNameDirect(AActionList, 'EditShapeAlignLeft'));
+          AddSubItem(FindActionByNameDirect(AActionList, 'EditShapeCenterHorizontally'));
+          AddSubItem(FindActionByNameDirect(AActionList, 'EditShapeAlignRight'));
           AddSubItem('-',nil,0);
-          AddSubItem(AActionList.ActionByName('EditShapeAlignTop'));
-          AddSubItem(AActionList.ActionByName('EditShapeCenterVertically'));
-          AddSubItem(AActionList.ActionByName('EditShapeAlignBottom'));
+          AddSubItem(FindActionByNameDirect(AActionList, 'EditShapeAlignTop'));
+          AddSubItem(FindActionByNameDirect(AActionList, 'EditShapeCenterVertically'));
+          AddSubItem(FindActionByNameDirect(AActionList, 'EditShapeAlignBottom'));
           AMenu.Add(item);
           item := nil;
         end;
@@ -332,7 +351,7 @@ procedure TMainFormMenu.ActionShortcut(AName: string; AShortcut: TUTF8Char);
 var foundAction: TBasicAction;
   ShortcutStr: string;
 begin
-  foundAction := FActionList.ActionByName(AName);
+  foundAction := FindActionByNameDirect(FActionList, AName);
   if foundAction <> nil then
   begin
     ShortcutStr := AShortcut;
@@ -489,7 +508,10 @@ procedure TMainFormMenu.Apply;
   AddMenus('MenuHelp',   'HelpIndex,-,HelpAbout');
   for i := 0 to high(FMainMenus) do
     if not FMainMenus[i].used then
-       FMainMenus[i].menu.Visible := false;
+       FMainMenus[i].menu.Visible := false
+    else
+       // Qt6: Force menu visibility to ensure it's displayed
+       FMainMenus[i].menu.Visible := true;
 
   ApplyShortcuts;