this version on my Macbook works, the problem is on my imac which is a similar setup. I open the app and initially looks normal but it reverts to a menu bar showing only FIREFOX, and becomes unresponsive. However if that window is minimized the menu bar reverts to its normal self, and an open second window functions normally. At close down I have to close each window separately , otherwise Firefox can trip up Shutdown or Restart. I've re-installed with no success.