I went to the Apple store yesterday with my Macbook Pro to test a Thunderbolt Display. The store assistant attempted to demonstrate it to me (I say attempted!), but he couldn't get it working. Basically, when he connected my MBP to the display with the Thunderbolt cable, it worked to an extent, but it wouldn't.... - fill the full resolution of the Thunderbolt display (2560 by 1440 pixels) in Mirror mode - my graphics card is meant to support external displays up to 2560 by 1600 according to this - http://www.apple.com/macbookpro/specs.html - it also wouldn't work when we closed the lid. The TBD just went blank. We tried it on two different Thunderbolt Displays. My MBP has all the updates required as far as I'm aware. Can anyone suggest what we might have been doing wrong? Does my Macbook Pro need to be connected to a power outlet to work with the Thunderbolt display correctly? By the end of the hour in the shop the shop assistant suggested that it may be a problem with my graphics card? I can't decide whether he's right or he just didn't know what he was doing! Also, since then, when I open iMovie on my MBP, the bar at the top of the screen (the one that says what program you have open) says that iMovie is open, but it does not display the actual workspace itself. When I click on Mission Control the iMovie workspace appears, but then minimises again when I click out of mission control. Any help would be great. That's the last time I let an Apple store assistant muck around with my computer!