Every once in a while Firefox's window status messes up. I have it maximized but then, while Windows still considers it maximized, it starts behaving as if it isn't maximized, i.e. clicking the edge of the window focus the window behind Firefox. When like this it also has a frame/edge around the window. If I press the restore button, Windows unmaximizes Firefox and then I can remaximize it back to normal... this is very irritating behavoir, any help.

Notes on my usage: > a lot of alt-tabbing > Windows 7 > I use Windows classic theme > this does not happen with any other program