Why doesn't F11 work on certain webpages?
On certain webpages, F11 works fine and I can go to and from Full Screen mode with no problem. But then on some webpages it doesn't work - I can hit F11 and nothing happens. But if I just switch tabs to a different webpage, I can suddenly use F11 again. For example, I've had this problem when I'm using certain apps on Facebook.
Note that this F11 problem only happens with Firefox. When I visit the same webpages with IE, F11 works with no problem.
Wšykne wótegrona (1)
If a plugin (e.g Flash) has focus then F10 and other keyboard commands won't work. You will first have to click outside the plugin. That is why you have to press ESC to leave full screen video mode.