If you have a really old MacBook Pro that can’t do AppleTV mirroring, and you have an AppleTV on your network, turn this checkbox *off* to keep the status bar icon from appearing and immediately disappearing every once in a while.
If you have a really old MacBook Pro that can’t do AppleTV mirroring, and you have an AppleTV on your network, turn this checkbox *off* to keep the status bar icon from appearing and immediately disappearing every once in a while.