Hello -
For whatever this is worth, using my Google Apps account, *which has a "." in the URL* (ie. http://mail.google.com/a/myname.tld), FireGPG displays neither a list nor buttons. In a traditional Gmail account (which, ironically, also sports a "."), it displays fine. I was under the impression that each and all Google Apps mail URL's would have a "." in them, but I cannot fathom another reasons why FireGPG would not work exclusively for Google Apps mail.