We have a common "list of buttons" UI pattern that is used for the context menu, site menu, promts/dialogs, and menulists. Some of these use <button> elements inside vboxes; others use <richlistitem> elements, and still others use custom bindings. Because of this, the styles for these buttons are more complicated than necessary, and the behavior is inconsistent. For example, some of the button lists can scroll and others can't. We should fix this by providing a single set of bindings and styles that can be used in all these places.
This work is happening for bug 618989.