Disabling MB display when connected to external monitor

It turns out that upgrading to Lion made me lose a feature I need. I'm hoping the collective wisdom of the MacRumors community can help me figure out a solution.

I have a 2010 MB Air and an external display.

I'd like to disable the Air's display without running the Air in clamshell mode, so that I could use the Air's keyboard and trackpad.

Before upgrading to Lion, I used a method explained by MacRumors forum member pinkoos, in this thread:
http://hints.macworld.com/article.php?story=20060607121656766

However, this trick works only in Snow Leopard, not Lion (which I'm running).

In fact, near the bottom of Apple's support page on clamshell mode,

http://support.apple.com/kb/ht3131

it says that when you open the Macbook, what happens next depends on your OS. If Snow Leopard, the MB's display stays off (which is what I want). If Lion, the MB's display turns blue for a second, then comes back on, and I'm right back where I started.

If absolutely necessary, I will acquire an Apple bluetooth keyboard and trackpad and run my Air in clamshell mode. But I'd rather not spend the money if I can avoid doing so.

If any of you can help, I'd be grateful!

Thanks,
Ron

 

Thanks, enigma2K. That does work. (For others who want to learn this trick, you can skip ahead to about the 7:00 minute mark in the video.)

It is really a shame that we have to resort to putting magnets on our macbook cases, when Windows has had this simple feature for at least 10 years.

Detrius, thanks, I followed your link and left feedback requesting this simple feature. I hope someone reads it!