In composer, we have two combo boxes on the toolbar (paragraph type, and font face). If you click on one of them to drop it down, then click on the other one right away, then the first dropdown is succesfully dismissed, but the second dropdown does not display correctly; it pops up behind the main window. You can see this by making the window narrow enough that half of the right-hand popup shows up outside the main window. There is an additional redraw problem with these combo boxes, which is that the part of the dropdown that is over the main content area fails to draw.
The behavior of 'eating' the event that should drop down the combobox is the defined XP behavior by the combobox. If this is completely unacceptable, we could add the "eating" of such events as an attribute in the nsILookAndFeel object, thus making it configurable. The dropdown paint issue is a known problem assigned to patrick.
There isn't an event 'eating' problem that I can determine. The real problem is that the popdown window (i.e. small native window) for the second combo box is layered wrongly; it shows up *behind* the main window.
Oh, that problem is a view problem Patrick knows about.
I can't find the duplicate bug, but this is a view issue - reassigning to beard
*** This bug has been marked as a duplicate of 21405 ***