I used to have an older MBA and MBP with an external Samsung monitor attached to it. I have no idea if that's the OS is the reason, but under Leopard I could attach the screen while closed, wake the MBA with an external mouse/keyboard so the external monitor would show up. Then I could open the MBA (for cooling reasons) without having the display on the MBA to turn on as well. Now I have the latest generation of MBA with Lion, same setup, but I cannot do so anymore and I cannot find a setting to change it back to as it was. So everytime I open the MBA it will turn on its display, which is annoying because I only want to work on one screen. Anyone knows a solution to this?? Thanks!!