.scrollProxy

A special object that gets created for type:"scroll" (or "scrollTop" or "scrollLeft") Draggables; this object manages the scrolling behavior, applying the necessary transforms or margins to accomplish overscrolling when necessary. The scrollProxy object has top() and left()getter/setter methods (and scrollTop()/scrollLeft() which are simply the inverse of top()/left()). If you need to get the scrolling velocity, make sure you've loaded ThrowPropsPlugin and set throwProps:true on the Draggable and then you can useThrowPropsPlugin.getVelocity(yourDraggable.scrollProxy, "top") to get the vertical scrolling velocity (use "left" for horizontal).
Implementation
    public function get scrollProxy():Object