Yeah, pretty much what they said. You'd first start off with a timeout=.05, then in a timeout loop have a this.timer=(this.timer+1)%3 (I picked that one up from one of Liquid's item scripts. It sorta moderates the cursor speed.)
Then use this.pos or something to keep track of the cursor position, with a %# (# is 1 higher than the max value).
Then use showimg, with x and y using screenwidth and screenheight (use division)
Then use something like
NPC Code:
if(keydown(key)&&this.timer=2){
script;
}
There. I also proved to myself I didn't forget what I was doing over my almost 2-month holiday.
All the same, hope that helps.