I am working with Photoshop CS6 on a retina 15" MacBook Pro, connected to a Cinema Display (non-retina). If I drag the app from the laptop screen to the external display and then resize the app window, the active window distorts dramatically and starts flashing and flickering. If I drag the app back to the laptop (retina), everything goes back to normal and looks fine. I tried quitting Photoshop on the non-retina display, and relaunching it so that it started there. It loaded up fine and appeared to be working correctly in "non-retina" mode, but now it no longer can display retina resolution when I drag it back to the laptop. I've tried relaunching, disconnecting the external display, rebooting, and even reinstalling Photoshop entirely, but the app seems to be permanently stuck in standard resolution and will not go back to retina.