The fixes fixes fix has a bug!

The changeset breaks almost every system window.  After filing in, I 
can no longer reliably mouse to a menu in a browser pane (the 
scrollbar widget disappears just as I mouse to it).

>I think, the whole hierarchy should be refactored to use only
>SelectionMenus but not PopupMenus because what the MouseMenuController does
>is to reimplement what SelectionMenus already do.

I'm still quite sure I don't understand the problem here.

Perhaps we should get down to first principles before chasing more 
bugs.  What, precisely, was the bug you were trying to fix?

I really don't see any conceptual problem problem with having a Menu 
class hierarchy beginning with PopUpMenu, providing core 
functionality of presenting a list menu, returning the index of the 
selection, and a subclass, SelectionMenu, which adds the service of 
retaining a list of objects, selectors or values associated with each 
item, returning the associated object.  Indeed, at least to me, it 
makes good sense to have both.