Luckily in the mentioned 140 you can now configure Firefox to show tabs in the sidebar, and then actually use the Tree Style Tabs sidebar instead, not showing the native tabs at all.
The built-in vertical tabs are awful. Hit F11 for full-screen and all of the chrome disappears except for the vertical tabs. Who would want that? I'll try Tree Style instead.
It's just annoying that firefox took away the original tree style tab's ability to hide the main tab bar...