The fullscreen API works fine. A website can display itself without any other clutter on the screen (with user permission). Unfortunately, it is no longer possible for a user on Mac OS X to cause the switch to fullscreen. The view menu (Firefox 21.0, for example, on OS X) still offers an "Enter Full Screen" menu item. Unfortunately, all it does is hide some of the chrome (it hides the menu bar and the title bar), leaving other bars (tabs, URL) still cluttering the screen.
It has been this way for a couple of years, if I recall correctly, and it is only a "feature" on OS X. Nothing is being done to change it, AFAIK.
I just tried this on Nightly and the chrome that's left behind (tabs + URL) slide up and out of the way within half a second of entering full screen mode, leaving nothing but the webpage on the screen. Are you sure that this isn't happening for you?
Re:Firefox 25 will get a major UI overhaul
by callahad on Wednesday June 05, 2013 @12:10PM
(#5826518)
Works great on Linux, but that feature is totally absent on OS X.
I'm using this add-on in the meantime, but it has other issues: https://addons.mozilla.org/en-US/firefox/addon/old-lion-full...
Yes, I'm quite sure. On OS X, I can get real full screen with Chrome, and I can get it with Firefox if the website itself initiates it. But the "full screen" in the View menu removes half of the chrome and leaves the other half. Useless.
It turns out I'm not the only one complaining. It has been a known issue since at least early 2012. Apparently, some of us think full screen should mean FULL screen. Nobody at Mozilla is working on it: https://bugzilla.mozilla.org/show_bug.cgi?id=740148
Re:Firefox 25 will get a major UI overhaul
by keeperofdakeys on Wednesday June 05, 2013 @10:25AM
(#5825759)
You might need to enable the "hide toolbar" option, which can be accessed by right clicking the toolbar in the right place while in full screen. I'm unsure if this option is available on OSX.
Furthermore, Firefox implements the HTML5 Fullscreen API, which gives the ability to websites themselves to request the full-screen mode, with a dialog pop-up that allows you to either deny, or to temporarily or permanently give this privilege to a website: https://developer.mozilla.org/en-US/docs/Web/Guide/DOM/Using...
So basically your full-screen HTML presentation can load in full-screen mode by itself, without the user having to make an explicit View action for it.
I find it hard to believe that you don't have it. If it's true, maybe it's a problem on OS X that will likely get fixed.