Fix menubar action after @Carreau's suggestion.

IPython/frontend/qt/console/qtconsoleapp.py

@@ -1126,7 +1126,7 b' class IPythonQtConsoleApp(BaseIPythonApplication):'
                 shortcut="Ctrl+Meta+H",
                 statusTip="Toggle menubar betwin visible and not",
                 triggered=self.toggle_menu_bar)
-            self.window_menu.addAction(self.toggle_menu_bar_act)
+            self.window.window_menu.addAction(self.toggle_menu_bar_act)
 
     def toggle_menu_bar(self):
         menu_bar = self.window.menuBar();