Laptops will output to external screen while closed, and all connected monitors brightness can be adjusted independently (to off if need be).
Exactly what can't be done?
Exactly what can't be done?
It seems to me that Apple's emphasis has been on using one screen well and applications like FCPX that use privileged APIs to use fullscreen well across monitors, but developers who use multiple displays in more complicated ways are pretty much stuck with third party solutions (I use SizeUp, and I used to use Cinch). This doesn't solve the issue you mention, but I'm very happy with it otherwise -- and when Apple incorporates the features of nice third-party utilities into the OS it gets lambasted from the other side.