[mark hunte]

Here is an old script I had,that you can play with.

It will check the idle state every 20 seconds.
if the idle state is less than 20 seconds ( i.e a key clicked in the last 20 seconds) then it will quit in this case textedit.app.

if the idle time is more than 120 seconds ( no key clicked for a minute and half) it will launch textedit.app

property idleCheck : 20 as integer
property idleCheck_usr : 120 as integer
set timer to 0
on idle
	--Check idle time
	set idletime to do shell script "ioreg -c IOHIDSystem | awk '/HIDIdleTime/ {print int($NF/1000000000); exit}'"
	set idletime to idletime as string
	set idletime to idletime as integer
	
	tell application "System Events"
		
		
		if idletime is less than idleCheck then (* 20 is 20 seconds. If a key was  tapped 
		within the idleCheck  seconds, it  quits the app. *)
			tell application "TextEdit" to quit
			
			return idleCheck -- checks again in ... seconds
		else
			if idletime is greater than idleCheck_usr then (*  If a key was tapped 
		after the idleCheck_usr  seconds it t opens the app. *)
				tell application "TextEdit" to launch
				
			end if
			
			return idleCheck -- 
			
		end if
		
	end tell
end idle