I can't find the add-on either, but I do know that the betas of Firefox 3.5 have a button beside the tabs to open a new one, like in your picture.
I think the removed it though its not in my 3.5 (ctrl+t) ftw
Network bridging gui <vote for that| my ideas : 1) show failed logins 2) Report file editing 3) Renice the active program ...etc
Bookmarks