Hello, I really have one problem with firefox, it is fullscreen mode on sites like youtube, twitch etc. When I go in fullscreen on this sites in chrome, safari, opera, then os x make a new desktop for it and I can swipe left from this fullscreen to my default desktop. So, normal spaces-feature behavior. In firefox when i press fullscreen button on any video site it just expand it in my current desktop. So, how can i do this simple thing in firefox? Thanks in advance.