QWidgetAction is not shown in main menu bar on MacOSX Snow Leopard

On Mac OSX 10.6.8 (Snow Leopard) using Qt 5, a QWidgetAction inserted into a submenu of the main menu bar is not displayed.

When using Qt 4.8.3, the QWidgetAction is displayed (though not correctly--see QTBUG-27163).

To reproduce, build and execute the attached project and click on the TEST main menu item in the menu bar. Notice that the only menu item visible is "Normal menu item". There are two QWidgetAction items that should be displayed above the "Normal menu item" but which are missing.

See the screenshots for examples of this test application built against Qt 5 and Qt 4.8.3. Note that the 4.8.3 build includes the patch provided in QTBUG-27163 which only fixes the transparency of the QWidgetAction in the menu.