Screenshot:

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

Are you using a Firefox version from the Mozilla server or a version that may have been configured specially and has some features disabled?

In the address bar, type the command you want and press enter. You could also add these to your bookmarks toolbar.

about:addons

about:config

about:crashes

about:preferences

Use about:about to see all the pages.

Starting Firefox in safe mode did show all the controls.

Probably these settings are blocked by my company - I could see mozilla.cfg file is modified.

Did you try the way, I suspect, most of us use to use? Right click on the Menu Bar.

alan_r said

Did you try the way, I suspect, most of us use to use? Right click on the Menu Bar.

Yes, I have tried it - the option is missing. Fun fact is when I scroll down through the menu using keyboard down button, it can open customize option like an arrow hitting the target in the dark.

motenagesh said

Starting Firefox in safe mode did show all the controls.

It could be the work of one of your add-ons. Type about:addons<enter> in the address bar to open your Add-ons Manager. Hot key; <Control>(Mac:<Command>)<Shift> A)

In the Add-ons Manager, on the left, select Extensions. Disable a few add-ons, then Restart Firefox.

Some added toolbar and anti-virus add-ons are known to cause Firefox issues. Disable All of them.

If the problem continues, disable some more (restarting FF). Continue until the problem is gone. After, you know what group is causing the issue. Re-enable the last group ONE AT A TIME (restarting FF) until the problem returns.

Once you think you found the problem, disable that and re-enable all the others, then restart again. Let us know who the suspect is detective.