The content button in the XBL at chrome://global/content/bindings/button.xml#menu-button has "accessKey" (uppercase "K") in its inherits list. But this should be "accesskey" (lowercase). This usually results in the accesskey not being underlined, although the key still activates the button. Also, if the accesskey comes from a command element, it becomes underlined on mouseover.
Created attachment 636409 [details] [diff] [review] patch
Thanks for the patch. Do you need help to check it in?
Yeah, I have no idea how checking is done.
If you set the 'checkin-needed' keyword on the bug, as I've done, someone may come along and check it in. If not, you can ask on the #developers irc channel for someone to.
Pushed to mozilla-inbound: https://hg.mozilla.org/integration/mozilla-inbound/rev/2ee8a6148b94 Nice job on your first patch Atte. If everything goes smoothly, your patch will be merged to mozilla-central within a day or two.