When i click fullscreen button on a flash video (for example video embedded from Vimeo) it opens fullscreen on the wrong monitor. Not the one on which the action has been started, but on my laptop built in screen. Extremely annoying as I can't get fullscreen flash running on my external monitor , which I use as my main one. In Chrome it works correctly (but I know it uses Pepper). I'm running Firefox 40.0.3, on Fedora 21 (Linux 4.1.6 . Gnome 3.14).