content: tell application "System Preferences"
  	activate
  	reveal anchor "displaysDisplayTab" of pane id "com.apple.preference.displays"
  	tell application "System Events"
  		delay 1
  		set value of slider 1 of group 1 of tab group 1 of window 1 of process "System Preferences" to 0.5
  		
  	end tell
  	quit
  end tell
  