Weird Firefox 4 GUI bug... how do I fix it?

Question

When JavaScript opens up a child window, the Firefox 4 tab bar messes up like this:

Note that the screenshot is NOT cut off... The tab itself is shifted up higher than it should be. When I restore the window (unmaximize it), and then maximize it again, the tab bar shifts back down to its normal position:

Has anybody else run into this bug, and how do I fix this? It's really annoying!

Answer 1

Yes, it's a bug.

No, I don't think there's any way to fix it. You can avoid it by somehow having the tab bar visible beforehand, though.