Got stuck in full screen on a windows laptop, same problem others had been describing and offered solutions failed or were unavailable to me. Eventually I figured it out. On this (Lenovo X1) laptop the F keys all have little icons for other stuff they do on them which does not actually trigger the F/Fn key functions. So what you do to trigger the F11 exit full screen function is to hold the 'Fn' key and press F11. Worked first time. Just tested to enter and exit full screen again, very easy. So it was an annoying problem and it should be in the context menu. Theres problem some way I don't know to make the menus appear. But once found, it was an easy way out. Not sure how it would work on my Mac Mini with a PC keyboard and I don't have an Apple laptop to check. But Fn+F11 does the trick no problem. Hope you found this answer first instead of all the others that don't seem to do it!