How to disable Now Fullscreen warning message in Firefox

Like any other browser, every time you play a video in full screen mode or run something that takes up the whole screen, Firefox will warn you. The message is displayed for a few seconds before disappearing. If you find this annoying, we will explain in this post how to disable the full screen warning message in Firefox.

Why does Firefox display a full screen warning message?

You can see a message like:

• You are now in full screen
• The website is now in full screen.

The full screen API can be activated when a usage initiates it. It can be either the keyboard or a mouse click. The API allows the website to offer a different version of the website or player that corresponds to the full screen method. This mode can be used by a phishing website to automatically switch to full screen and provide an interface that may look like the real website.

Remember that this is different from the F11 function or the full screen mode of Firefox. Here we’re talking about video players or something similar that goes full screen when users press a shortcut or use the mouse.

Disable full screen warning message in Firefox

We will need to access the advanced preferences page, also called the configuration page. These pages are generally not intended for use by everyone and make changes with care. If you change the wrong setting, you will have to reset the browser and you may lose all of your profiles.

1. Open a new tap and tap about:config in the address bar and then pressing the Enter key
2. The page that then loads will notify you of the result of changing the basic preferences. Click on the “Accept the risk and continue” button.
3. In the next screen, use the search bar to find full-screen-api.warning.timeout
4. When it appears, click the pencil icon next to the setting to change the value
5. The value accepted by the parameter is in milliseconds. You can set the value to zero to completely disable it.

However, if you want to reduce the time remaining, you will have to experiment a bit to understand it. I would suggest keeping the timing so that you can at least see for a second. This will be useful if you unfortunately land on a bogus website.

Once that’s done, the next time you go to full screen on a video, you won’t see any warnings.

That said, if you want to go back, go back to the same setting and click the reset arrow to go back to the default.