AS3: Scroller

// grab its top position before we scroll anything
private var contentStart:Number = content_mc.landPort.content_mc.y;
private var dragRatio:Number;
 
// add the mouse_down to the scrollArrow and add the mouse_up to the stage
scrollArrow.addEventListener (MouseEvent.MOUSE_DOWN, drag);
this.addEventListener (MouseEvent.MOUSE_UP, dragOff);
 
private function drag (evt:Event):void
{
	// figure out how far the content needs to move for each pixel the scrollArrow moves
	dragRatio = (content_mc.height-contentMask.height) / (scrollerTrack.height-scrollArrow.height);
 
	// define where the scrollArrow can move within
	var rectangle:Rectangle = new Rectangle(scrollArrow.x, scrollerTrack.y, 0, scrollerTrack.height-scrollArrow.height);
 
	// listen for scrolling and start dragging
	this.addEventListener (MouseEvent.MOUSE_MOVE, dragging);
	evt.target.startDrag (false, rectangle);
}
 
private function dragging (evt:Event):void
{
	// figure out where the content needs to scroll to and tween it
	var nextPos:Number = contentStart-((scrollArrow.y-contentStart)*dragRatio);
	TweenMax.to(content_mc, .5,{y:nextPos});
}
private function dragOff (evt:Event):void
{
	// quit yo draggin
	evt.target.stopDrag ();
	this.removeEventListener (MouseEvent.MOUSE_MOVE, dragging);
}