I just got a Dell 24" screen to use as a second monitor with my 27" iMac. My problem is that when I open Starcraft 2 and hit command+M to make SC2 fullscreen, it makes my new second monitor go black instead of keeping the windows and desktop open. I've heard that people can keep this second monitor available while playing in full screen mode. That's apparently how the pro's keep an eye on their stream chat and answer questions on the fly during a game. So how do I keep my second monitor from going blank on me?