Hopefully this isn't a dup.

If you create MenuButton and add two instances of Menu (hereafter referred to as "sub menus") to its items list, the sub menus don't behave correctly. Upon dropping the MenuButton for the first time, you will see a sub-menu popup as you hover over the first sub menu control and will also see the correct popup when you move the mouse down over the second sub menu. Everything works fine up to this point. However, if you then move the mouse back over the 1st sub menu and hover, its popup doesn't display. If you then close the menubutton popup entirely and then re-drop the menubutton's menu, you will notice that the first sub menu's popup still fails to display when you hover over it. The second sub menu seems to always work.

See attached example app.