Rated 3 out of 5 stars

Great concept, much needed. Unfortunately, ran into problems with this extension. Sometimes it makes the FF window not appear, or it always flashes once when FF runs (appears for a split second then disappears, then appears 2 seconds later). On uninstall, it leaves some crap in the userChrome.css files (tsk tsk!). Anyway, barring these quirks, it seemingly worked OK (I really just wanted it for showing the titles of the icons in the bookmark toolbar items in the tooltips, I didn't care for the show labels on mouseover for very long).