Думаю не нужен здесь hitPoint. Просто контролируйте момент драга. Что-то вроде этого:

Код AS3:
import flash.events.MouseEvent;
mc.stop();
var _isDrag=false;
// DRAG
mc.addEventListener(MouseEvent.MOUSE_DOWN, mcMouseDown)
function mcMouseDown(e:MouseEvent):void
{
stage.addEventListener(MouseEvent.MOUSE_MOVE, stageMouseMove);
stage.addEventListener(MouseEvent.MOUSE_UP, stageMouseUp);
_isDrag=true;
}
function stageMouseUp(e:MouseEvent):void
{
stage.removeEventListener(MouseEvent.MOUSE_MOVE, stageMouseMove);
stage.removeEventListener(MouseEvent.MOUSE_UP, stageMouseUp);
_isDrag=false;
}
function stageMouseMove(e:MouseEvent):void
{
mc.x=stage.mouseX;
mc.y=stage.mouseY;
}
//OVER OUT
mc.addEventListener(MouseEvent.ROLL_OVER, mcRollOver);
mc.addEventListener(MouseEvent.ROLL_OUT, mcRollOut);
function mcRollOver(e:MouseEvent):void
{
mc.gotoAndStop(2);
}
function mcRollOut(e:MouseEvent):void
{
if(!_isDrag) mc.gotoAndStop(1);
}