As a Windows user, I don't completely understand how Firefox runs on Mac, but for what it's worth:

Issue #1: If the cursor is in the address bar when you go to full screen, the toolbar area doesn't hide. Click out of the address bar, then exit full screen and enter it again.

Issue #2: Firefox has a switch for whether to hide the toolbar area in fullscreen. You can double-check that here:

(1) In a new tab, type or paste about:config in the address bar and press Enter/Return. Click the button promising to be careful or accepting the risk.

(2) In the search box above the list, type or paste FULLS and pause while the list is filtered

(3) If the browser.fullscreen.autohide preference is bolded and "modified" or "user set" to false, double-click it to restore the default value of true

Was that relevant?

Hey @jscher2000, thanks so much for your detailed reply!

Unfortunately, neither of those options work :(

At this point, I'm not even sure if FF on Mac even allows the tabs and address bar to get hidden!

Some features are different on Mac and Linux than they are on Windows, but you still should have some kind of full screen feature...

Does it matter which method you use:

• (menu bar) View > Full Screen
• menu button > Full Screen button at the end of the "Zoom" controls
• Command+Shift+F

Hey mister, thanks for your quick follow-up once again. Unfortunately, all three methods just work the same way.

Wish I had another Mac to test if it's somehow my configuration which is making it glitch. No luck even with freshly-downloaded, un-modified install of FF.

Thanks for your help though!

To test configuration, you could try:

New Profile Test

This takes about 3 minutes, plus the time to test full screen.

Inside Firefox, type or paste about:profiles in the address bar and press Enter/Return to load it.

Click the Create a New Profile button, then click Next. Assign a name like April2019, ignore the option to relocate the profile folder, and click the Finish button.

After creating the profile, scroll down to it and click the Set as default profile button below that profile, then scroll back up and click the Restart normally button. (There are some other buttons, but please ignore them.)

Firefox should exit and then start up using the new profile, which will just look brand new. Please ignore any tabs enticing you to connect to a Sync account or to activate extensions found on your system so we can get a clean test.

Does full screen work any better in the new profile?

When you are done with the experiment, open the about:profiles page again, click the Set as default profile button for your normal profile, then click the Restart normally button to get back to it.

Hello, thanks again for trying to help out with this troublesome issue, and sorry for all the trouble.

I followed all your steps, and no luck—it unfortunately looks like maybe stock FF on Mac doesn't allow hiding the address bar/tabs. I'm honestly surprised how such a basic thing isn't part of the app.

Thanks again for your detailed instructions and kind attempt to solve my problem!

See this topic.

Hi @TyDraniu, thanks for sharing your idea! This is definitely a good fix for now, and it makes the website fill up my screen rather nicely.

That said, I will keep hoping for another solution or extension which makes it possible to auto-hide the tabs and address bar, and show them again on taking my mouse to the top of the screen (as it happens in Safari).

Thank you anyhow, will use your nice bookmarklet for now!

Did you try the extension mentioned further down in that thread?

• Fullscreen Plus https://addons.mozilla.org/firefox/addon/fullscreen_plus/

Note that some extensions aren't working on Mozilla website because of CSP rules.

@cor-el, thanks for sharing, but it unfortunately just does what the normal menu bar fullscreen button does, without hiding address bar/tabs.

I installed the add on, and it didn't do anything at all? anyone able to help?

Keep in mind that web extensions do not work on Mozilla websites (you can't inject JavaScript files) if you only tried it there.