Search Support

Avoid support scams. We will never ask you to call or text a phone number or share personal information. Please report suspicious activity using the “Report Abuse” option.

Learn More

Full screen does not go completely full screen, black bar.

more options

I always have Firefox in full screen. When I first open Firefox, it does not go completely full screen. It will leave black bars on the right and bottom portion of the screen. I will then have to press F11 to exit out of full screen and then F11 again to return to full screen, which solves the problem. I will have to do this every time I close and then re-open Firefox. I have disabled Add-ons, tried in safe mode, removed hardware acceleration, and all other suggestions on the support page. None of which helped. What is causing this problem. Thank you.

I always have Firefox in full screen. When I first open Firefox, it does not go completely full screen. It will leave black bars on the right and bottom portion of the screen. I will then have to press F11 to exit out of full screen and then F11 again to return to full screen, which solves the problem. I will have to do this every time I close and then re-open Firefox. I have disabled Add-ons, tried in safe mode, removed hardware acceleration, and all other suggestions on the support page. None of which helped. What is causing this problem. Thank you.
Capturas de pantalla anexas

All Replies (4)

more options

Start Firefox in Safe Mode to check if one of the extensions (Firefox/Tools > Add-ons > Extensions) or if hardware acceleration is causing the problem.

  • Switch to the DEFAULT theme: Firefox/Tools > Add-ons > Appearance
  • Do NOT click the Reset button on the Safe Mode start window

Try to rename (or delete) the xulstore.json file in the Firefox profile folder. You can use this button to go to the currently used Firefox profile folder:

more options

Thank you for your help cor-el. I have tried your solutions but they have not solved the problem.

more options

Can you drag the window wider if you leave maximized mode?

more options

Yes I can do that. This problem only happens when I first open Firefox or close Firefox and then reopen it. Firefox remembers the window size after closing and and then always reopens in your last window size state. If I don't have the window in full screen mode when I close, it opens normally. When I press F11 (to leave full screen mode) and then F11 to return, the resizing back to full screen mode will solve the problem.