[flexcoders] Possible to cancel a tooltip event?

[G]

I am trying to cancel a tooltip event (I only want it to display when the mouse 
is hovered over a certain area), and can't seem to figure it out. I tried 
stopPropagation, preventDefault, and stopImmediatePropagation, but none of them 
seem to work.

Here the code I am using:

        private function toolTipCreateHandler(event:ToolTipEvent):void {
            if(event.currentTarget.mouseX < 130) {
                var tooltip:PhotoToolTip = new PhotoToolTip();
                tooltip.src = event.currentTarget.toolTip;
                event.toolTip = tooltip;
            }
            else {
                event.stopImmediatePropagation();
            }
        }   

Any ideas?

Thanks