No Frills Fullscreen

When you press F11 to put Firefox into fullscreen mode, it doesn't hide the navigation toolbar.

There are two existing extensions to fix this, but they're overly complicated and do lots of other things too, like projection mode for slideshows.

→This extension← does nothing more than hide the toolbar, like so:

window.addEventListener("fullscreen", function(e){
    var navbar = document.getElementById("nav-bar");
    navbar.hidden = ! navbar.hidden;
}, false);