[error] NameError (name 'onEvent' is not defined)

I am pretty new at this so this may be a bit of a kludge, but maybe something like this:
    #Set screen regions to improve search speed somewhat. Divide into halfs and quarters.
    #TopHalf, LowerHalf, LeftHalf, RightHalf, TLQuarter, TRQuarter, BLQuarter, BRQuarter

    x = getX()
    y = getY()
    w = getW()
    h = getH()

    rTopHalf = Region(x,y,w,h/2)
    rTopHalf.highlight(1)
    rLowerHalf = Region(x,h/2,w,h/2)
    rLowerHalf.highlight(1)
    rLeftHalf = Region(x,y,w/2,h)
    rLeftHalf.highlight(1)
    rRightHalf = Region(w/2,y,w,h)
    rRightHalf.highlight(1)
    rTLQtr = Region(x,y,w/2,h/2)
    rTLQtr.highlight(1)
    rTRQtr = Region(w/2,y,w/2,h/2)
    rTRQtr.highlight(1)
    rBLQtr = Region(x,h/2,w/2,h/2)
    rBLQtr.highlight(1)
    rBRQtr = Region(w/2,h/2,w/2,h/2)
    rBRQtr.highlight(1)

    if not rTRQ.exists(yourseach.png):
        popup("Something not found")
        doAction
    else:
        popup("Something Found")
        doOtherAction

Could have sworn I replied to this yesterday, but is not in here.

Yes, I know I can actually carve up the screen or even define a region that contains my target. What I wanted was the ability to get an observer running that could run in the background and check for my particular target, then call an event routine to process the event.

The onAppear() scans the entire screen, given the size of my real estate, it would consume a lot of processor scanning the screen when I already know where it will appear. The documentation talks about the onEvent restricting to a regions rectangle which would be perfect if it worked.

I suppose the alternative is to fire off threads to do the processing then try to figure out how to shut everything down at once without having to kill the IDE everytime.

onEvent is just a placeholder for the on... functions.
Use someRegion.onAppear()