On Windows, the full screen mode usually removes all the toolbars and displays just the site, edge to edge. However, if you move your mouse pointer all the way to the top of the screen, the tab bar and main navigation toolbar should slide down temporarily (when you move your mouse away from them, they should slide back up).

Your tab bar and main toolbar aren't sliding up??

The problem remains. I may have klicked ate something close to the fullscreen button in the orange Firefox box in the top left corner. When I try to enable it in high speed whit the mouse. Thank you for helping me whit this problem.

Could you try F11 in Firefox's Safe Mode? That's a standard diagnostic tool to bypass interference by extensions (and some custom settings). More info: Diagnose Firefox issues using Troubleshoot Mode.

You can restart Firefox in Safe Mode using

Help > Restart with Add-ons Disabled

In the dialog, click "Start in Safe Mode" (not Reset)

Any difference?

Thanks!

Hi madmats, you probably won't be able to run in Safe Mode permanently because you'll miss one or more of your extensions.

You can review and manually disable nonessential and unrecognized extensions on the Add-ons page. Either:

• Ctrl+Shift+a
• orange Firefox button (or Tools menu) > Add-ons

In the left column, click Extensions. Then, if in doubt, disable.

Usually a link will appear above at least one disabled extension to restart Firefox. You can complete your work on the tab and click one of the links as the last step.

Hopefully that will cure it.

P.S. One other thing that Safe Mode does is ignore any customizations created in a userChrome.css file. This file only exists if it was specifically created on your system, but if you did create one, it could affect the screen layout in full screen mode.

To see if you have it, open your current Firefox settings (AKA Firefox profile) folder using

Help > Troubleshooting Information > "Show Folder" button

Can you find a folder named chrome? If you don't see one, you don't have a userChrome.css file. If you do see one, click into the chrome folder and see what you find.

You can right-click on empty space on toolbars in full screen mode and make sure that "Hide Toolbars" has a tick (pref: browser.fullscreen.autohide).