Options for fixing the problem with Firefox and menu button

Matt,

The problem with Firefox is related to changing the state of aria-expanded on the menu button when the menu button is a BUTTON element.  For some reason when you change the value of aria-expanded it generates an onclick event on the BUTTON element which in the case  opens the menu.   But this only seems to happen when the SPACE key is pressed, not for any other key and only if the BUTTON element is used for the menu button.   If we use anything other than button the problem goes away for Firefox.

Two options to fix the problem:
1. Don't use the BUTTON element for the menu button
2. Don't use the aria-expanded on the menu button

What do you think we should do?

Jon