When I Quit firefox in fullscreen mode, then it startups in maximized mode NOT fullscreen
In mac os x in firefox developer version I always quit Firefox in full screen mode with many or some open tabs. When I open up it again it starts with maximized mode mode instead of full screen mode that I leaved it.
Currently, it doesn't appear that Firefox can start in fullscreen mode automatically. If you are in fullscreen mode when you close, you can only restart in maximum mode.