I know on the old style ACD's (the aluminum ones) you could put the system to sleep by hitting the power button, you can enable this functionality by going to system preferences -> display -> options
I know on the old style ACD's (the aluminum ones) you could put the system to sleep by hitting the power button, you can enable this functionality by going to system preferences -> display -> options
i think you have to have the MacBook in clamshell mode (read my post earlier) for the Options to show up and set the power button to show the shut down window.
You have to have FW (I think it's this) or USB plugged in for that to work, and I see from your picture that you do. That's weird, the option did come up for me when I had my MBP plugged into mine. Now both my ACDs are plugged into my Hackintosh and the options menu is still there (for each display).
Edit: Try hitting detect displays and see if that makes it pop up.