When firefox is maximized if i enter fullscreen mode (e.g. with F11, or open video in fullscreen) and then exit it, firefox becomes unmaximized with a little gap between window borders and screen borders. I searched for it, but found nothing. I use ubuntu 18.04 on xfce, and didn't experience that kind of problem on Gnome or KDE. I don't even know if it's a WM issue, or something wrong with firefox. Maybe somebody knows how to fix it?
2 Answers
Its a bug in current (64) version related to CSD support. This will be fixed once you upgrade to 65 or 66 (depends on release schedule).
I have the same problem in Centos 7.6. A workaround is to unmaximze the window before you press F11. Then you manually make the window as big as it would be when you maximize it. Next you press F11. And when press F11 again it returns to the size it had before the fullscreen.
