When one menu in the menubar (not a screen menubar) is empty and you select it, when you mouse over the other menus they won't show anymore. E.g. If you have Menus A,B,C in the menubar and only C is empty, show Menu A then move the mouse over to highlight menu B - it shows the menu, then move to the empty menu C, it is empty and nothing shows. Now move back to B, nothing shows, back to A, nothing shows. As soon as the popup for an empty menu is triggered no further menu popups are shown until the menu highlight is disengaged entirely and you start again.