* my PC is connected with an amp on 2nd hdmi for Sound-output.
* amp act like a Monitor/TV so i guess its a general multi screen issue.
* GPU (GTX 260 latest drivers) is setup to "expand" screen and both (mainscreen and amp) run at same resolution 1080p.
* When the cursor moved out of screen and you (accidantly) click on 2nd screen it will minimize your game (normal windows logic)