Comment 6 for bug 917753

(That you can't erase/edit your own bug comment is bug 80895.)

So the Firefox behavior seems to be this: There are no access keys for any item (not even the static ones like "Bookmark This Page"). But typing any character will highlight the next item, after the currently highlighted item, that starts with that character.

For example, if you have three bookmarks in the menu, "Aardvark", "Abacus", and "Bobbie", opening the menu and typing "ab" won't highlight "Abacus", it will highlight "Aardvark" then "Bobbie". But opening the menu and typing just "b" won't highlight "Bobbie", it will highlight "Bookmark This Page". Typing "b" repeatedly will highlight "Bookmark All Tabs", then "Bookmarks Toolbar", then finally "Bobbie".

This is rather crude behavior, but perhaps we could copy it for menus that contain no items with access keys.