This app was removed from the App Store.
Blackout – Display Manager
Mac OS Utilities
Blackout lets you turn off your displays with just a single click!
Blackout is aware of Mission Control:
If you enter Mission Control, Blackout will re-activate all turned off displays in a dimmed mode, so you can access, organize and move all open application windows. As soon as you leave Mission Control, Blackout will deactivate all turned off displays again.