When I start up Firefox on Ubuntu running Gnome 3.6 classic or whatever they call it, I got the traditional firefox and definitely no tabs in the title bar, a bunch of vertical space used for the menus, address field and search field and the list goes on. I was able to customize the bars in order to move everything onto one line but couldn't make it the same line as the menu, and could only find bugzilla entries about not being able to move tabs to the title bar on Linux.