Script to turn to black any other screen except the one with full screen application, in a multi-monitor setup.
Usage: simply call it. It checks for the current active window. If it is in full screen mode, the script turns to black any other screen except the one where the full screen application is running. Call it a second time (or with "on" parameter), to revert the effect in every monitor. Assign it to a keyboard global shortcut and you can call it whenever you want.