How to Disable Internal MacBook Display When External Display Is Attached

Mac OS X Hints:

Before Lion it was possible to run an external display off a laptop and have the internal display disabled, even if you opened the lid. This can be useful for a myriad of reasons including energy saving and better Wi-Fi reception. With Lion the internal display will always turn on when the lid is opened, even if there is already an external display connected.

I just ran into this after upgrading my main machine to Lion. A little nvram command-line jiggery-pokery does the trick.

★ Thursday, 20 October 2011