Another particular nagging problem with Firefox is that "full screen doesn't even hide the tabs or address bar (just the OS X bar, assuming you're using OS X).

Another particular nagging problem with Firefox is that "full screen doesn't even hide the tabs or address bar (just the OS X bar, assuming you're using OS X). It would be nice if you can add a way to change Firefox's settings so that, in full screen, the only thing visible is the web page.