• I use Mavericks (or later versions of MacOS X) and my display doesn't disable completely
    The disable function is partially broken by Apple in Mavericks. More precisely:

    With the option to use separate spaces in Mission control enabled, then an external "disabled" screen can keep showing the desktop picture but becomes inaccessible with the mouse cursor, and will never update any more. It's disabled, but not blanked.
    With the option to use separate spaces in Mission control disabled, then the "disabled" screen will generally show a white pattern, but will also be inaccessible with the mouse cursor. It's better but still not like Mountain Lion.

    That said, in both cases, once the display has been "deactivated" and if you put the Mac into sleep, then wake it up again, the Display is still inactive and stays completely dark.
    There is no way to change this for now. Maybe a future OS X release will correct this again the way it was on Mountain Lion.

    With SwitchResX 4.5, you'll get following options to enhance the experience:
    - you can set all displays to sleep automatically when disabling any display. However, this forces you to wake them up manually
    - you can set SwitchResX to darken the displays automatically after a display has been disabled, and after a configurable time
    - you can set SwitchResX to set the brightness of the disabled display to zero (however this is only possible on some displays who support setting their brightness via software)