You don't use those menus, do you? Good, because now you can't in ChatZilla on current Mozilla and Firefox builds! The menus vanished mysteriously one morning, after DOM Inspector got a menu hack-attack. If it weren't for a slight problem with :empty, it'd be ok, but it's not.
Edit: bsmedberg had a good idea to hack around the :empty problem, which I've done into a patch. Hopefully this will be fixed soon in trunk (and will be in 0.9.68.6).