Wouldn't recommend for FF4 Rated 4 out of 5 stars
If you try the trick described below: I got serious trouble resulting in the menu bar being visible but not usable and finally all my toolbars were blank. On top of that some history was missing and a recent addition to my bookmarks. The restart option is not visible in the mini-menu you get when you turn off the menu-bar so you will have to use the keyboard or add the button. Better wait for a true and tested version wich I hope will come soon.