Disabling the Firefox full-screen animation and popup

Note: I’m using Firefox 149.

To disable the full-screen animation and popup that get triggered when you press F11, which I personally found annoying, do the following:

1. Type about:config in the address bar and press Enter to open the advanced config window.

2. It will, most likely, prompt you for confirmation before going ahead. Click “Accept the Risk and Continue”.

3. Type full-screen-api in the search bar to filter the options.

4. And perform the following changes:

   Key	Default value	New value
   full-screen-api.transition-duration-enter	200 200	0 0
   full-screen-api.transition-duration-leave	200 200	0 0
   full-screen-api.transition.timeout	1000	0
   full-screen-api.warning.delay	500	0
   full-screen-api.warning.timeout	3000	0

For “advanced” Firefox users

If you know how to modify the prefs.js file, add these lines:

1user_pref("full-screen-api.transition-duration.enter", "0 0");
2user_pref("full-screen-api.transition-duration.leave", "0 0");
3user_pref("full-screen-api.transition.timeout", 0);
4user_pref("full-screen-api.warning.delay", 0);
5user_pref("full-screen-api.warning.timeout", 0);

If you don’t, just follow the instructions above.

Or, if you want to learn how to do it this way, read this 2024 Super User question.