Mozilla improves Firefox's full screen handling

Martin Brinkmann
Aug 24, 2015
Updated • Nov 4, 2015

Mozilla tweaked Firefox's full screen behavior in recent Nightly versions of the browser (that is version 43) to make it less annoying to users.

Some sites allow you to run applications or services in fullscreen. Many video streaming services such as YouTube or Twitch offer full screen options to stream videos in full screen.

This fullscreen option should not be confused with running the browser itself in fullscreen mode. The latter is toggled with a tap on the F11 key on the keyboard.

Firefox users who have made use of that option until now had to permit full screen mode explicitly each time it was activated on a site supporting it. This meant that the video would not start streaming before explicit permission was given with a click on the allow button.

Firefox offered two options until now to get around this. Site permissions allow you to set specific permissions for select sites, and one of the permissions is full screen mode. If you set it to allow, the prompt to allow it on activation is no longer displayed for that site.

youtube is in fullscreen

The same option is displayed on the prompt when you activate the fullscreen option on a site. All you had to do was check the "remember decision" button to save the permission change.

The second option was to set the preference full-screen-api.approval-required to false. This disabled the approval requirement for all sites and services.

firefox fullscreen mode

The change removes the explicit action from the process. A prompt is still displayed when fullscreen mode is activated on a site like YouTube, but it won't require explicit permission to run anymore.

Firefox displays a short prompt revealing that the site is running in fullscreen mode and that the mode can be exited again with a tap on the Esc key on the keyboard.

exit full screen

The prompt disappears after a couple of seconds and won't come up again until you exit fullscreen mode and re-enter it at a later point in time.

The feature landed in Firefox 43 Nightly and the target milestone for it is Firefox 43. That's three release cycles for stable versions of the browser, two for beta and one for Developer editions if things go as planned.

Please note that Mozilla removed the fullscreen preference on Firefox's about:config page as a consequence as it is no longer needed.

Update: Apparently, there is still a preference available to define fullscreen behavior and turn it completely off. This works in Firefox 43 or later only. What you need to do is set the preference full-screen-api.warning.timeout to a value of 0 on about:config.

Mozilla improves Firefox's full screen handling
Article Name
Mozilla improves Firefox's full screen handling
Mozilla changed Firefox's fullscreen activation behavior in version 43 by removing the activation prompt when entering fullscreen mode.

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  1. chong boey chang said on January 4, 2017 at 3:41 am

    i want full screen

  2. Sameer said on July 3, 2016 at 4:45 pm

    Thanks for the article. I was highly irritated by the pop up. Why the hell does browser need to tell me if I am entering in the full mode ?

  3. fokka said on August 27, 2015 at 1:12 am

    ok, i found this bug on bugzilla that mentions the long black screen during full screen transition:

    there they mention to set full-screen-api.transition-duration.enter to “0 0” (zero zero) to disable the transition. default is “200 200”, that’s milliseconds i reckon. it feels much longer than 200ms though with default values.

    this disables the black screen during transition when going into fullscreen, but there’s still the black screen when exiting full screen. so it’s only a half win. the transition is also more jerky than eg. in 41 beta, where it isn’t ultra smooth, but lightning fast, so the implementation in 43 nightly feels like a regression.

    1. TekWarfare said on September 23, 2015 at 8:51 pm

      Just toggle “browser.fullscreen.animate” to false. If it doesn’t exist then create a boolean. Otherwise, set “full-screen-api.transition-duration.leave” to “0 0” as well.

  4. fokka said on August 27, 2015 at 12:44 am

    ok, i guess that is a less nagging solution for novice users and it’s good you can still prevent the message from appearing by setting full-screen-api.warning.timeout to 0, but the new full screen transition takes forever. it fades to black for about a second before it resumes showing a picture, both when going into full screen and when exiting it. this is arguably more annoying than the full screen message itself. i hope they fix that soon.

    1. Pants said on August 27, 2015 at 3:20 am

      Have a play … don;t know if this will work since mozilla are changing things and I don;t have a v43 here, but search for fullscreen in the about:config – there is a browser.fullscreen.animate setting – try setting this to false to speed things up

      1. fokka said on August 27, 2015 at 6:23 pm

        thanks for the tip, it doesn’t seem to change much though. maybe the black screen lasts a bit shorter, but the duration is not totally consistent, so i can’t say for sure. still slower and more jerky than in the beta i’m normally using.

  5. Florent said on August 25, 2015 at 5:06 pm

    For now i use an extension call “Disable HTML5 Fullscreen Alert”.
    That’s do exactly like the name said.

  6. greg said on August 25, 2015 at 4:09 am

    wait a minute. I can no longer disable that annoying prompt? Is there some other way to make up for not having the about:config setting? I hate that when I full screen and firefox keeps covering up what I’m trying to watch.

    1. Pants said on August 25, 2015 at 10:26 am

      Someone else brought this to my attention, so if anyone with a FF43 wants to test it

      // user_pref(“full-screen-api.warning.timeout”, 0); // FF42+ ?

      1. Paul said on September 24, 2015 at 1:29 am

        There is no such item in FF 42.0b1. And “full-screen-api.approval-required” is absent. Does someone know how to disable warning in this FFversion? sorry for my English.

      2. fokka said on August 27, 2015 at 12:39 am

        appearently not, i just changed the key in about:config (duh).

      3. fokka said on August 27, 2015 at 12:23 am

        do you add this as a userstyle or something?

      4. Martin Brinkmann said on August 25, 2015 at 11:35 am

        Works in recent Nightly (43). Disables the new fullscreen warning.

  7. Dave said on August 24, 2015 at 7:33 pm

    After their decision to axe XUL add-ons, nothing they do matters any more.

    1. Robert said on August 24, 2015 at 8:47 pm

      I wish there was a way to turn off updates for Firefox in Linux Mint.

      1. Sven said on August 24, 2015 at 10:38 pm

        No big deal, Linux can do that. You can pin a version of an application in your package management.

      2. Dave said on August 24, 2015 at 10:10 pm

        Can you make the Firefox folder read-only? LMDE is my favourite version of Linux :)

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