This issue can be caused by an extension that isn't working properly.

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

• https://support.mozilla.org/kb/Safe+Mode
• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes

Try hitting F11.

randym3570 said

Whenever the mouse falls below the top "heading lines" (toolbars?) containing the web tabs and web addresses ... that info is covered up by the web page being pushed up and covering it in order I suppose to give me more view of the web page... well I don't want that!!!!!!! It is very, very distracting.... I need to stop it or stop using Firefox!!!!!!!!!!!!!!

Hitting F11 Worked! and if I want the fuller screen back I hit F11 to toggle the feature back! Great... Is trick listed anywhere?

cor-el said

This issue can be caused by an extension that isn't working properly. 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

• https://support.mozilla.org/kb/Safe+Mode

Might work.... did not try it ... tried F11 first because it was easier, and it worked....

• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes

Sounds that you were running Firefox in full screen mode.

• https://support.mozilla.org/kb/how-to-use-full-screen

If you are in full screen mode then hover the mouse to the top of the screen to make the Navigation Toolbar and Tab bar appear.
Click the Maximize button (top right corner of the Navigation Toolbar) to leave full screen mode or right-click empty space on a toolbar and choose "Exit Full Screen Mode" or press the F11 key.