Quote Originally Posted by vasa1 View Post
Just to be clear, when you start Firefox, the top frame is there. Then while you're browsing, the frame disappears.

When you say "eventually" is it a long time? Does it involve active browsing or does it go away even if Firefox is open but not being used?

Can you correlate it with any action on your part? For example, in the two images you provided, the "normal" one doesn't have the find bar at the bottom. The problematic one does.

Do you have other options when you log in? My thinking is that while Firefox will be the same, you may get an idea of whether this problem is related only to GNOME Classic or not. For example, do you have the GNOME Classic No Effects option? If so, what happens when you run Firefox?
Yes, this can happen when not browsing, perhaps while I am running another application. There does not appear to be any rhyme or reason to the disappearance. Glad to see that someone else has seen the problem. I am not alone. BTW, I have not seen this happen in my Mint installation of FF, only the Ubuntu. (Just to be clear, I am running Gnome Classic and not Unity. I find Unity somewhat off-putting, annoying really).