Mozilla/5.0 (Macintosh; Intel Mac OS X 10.6; rv:2.0b4pre) Gecko/20100813 Minefield/4.0b4pre There is no keyboard shortcut to open the TabView display. You are forced to go to View | TabView right now. Having a shortcut like Cmd+E would be great.
Well, the shortcut Alt+Space works on OS X but there is no shortcut shown in the menu. Applies to all platforms.
It's ctrl-alt-space (ctrl-space on Mac), see bug 586753. But it's indeed not in the menubar.