How do I get my AirPlay mirroring to take up my entire TV screen? I have a 2011 27" iMac that currently has Mountain Lion installed on it, and I am trying to get the AirPlay mirroring to take up my entire 1080p widescreen TV.  How do I get that to happen?
Try setting the Match Desktop Size To setting in the AirPlay menubar item to Apple TV



If that doesn't work, it may be that AirPlay is outputting at 720p and your TV isn't scaling - perhaps try a stretch or scale mode on your TV.