Firefox will not leave fullscreen mode by using the F11 key.

Issue

• Unable to leave fullscreen mode in Firefox (F11 key) even after Firefox is restarted.
• When Firefox is put into full screen mode (by pressing F11 key), it is closed, and then subsequently re-launched, it gets stuck in full screen mode.

• When it is in this state pressing F11 will not revert Firefox back to it's normal screen mode.

  Steps to reproduce

  • Start Firefox
  • Press F11 to enter full screen mode
  • Close Firefox without leaving full screen mode
  • Start Firefox again
  • Try to exit full screen mode by pressing F11