Я использую этот код.
import flash.display.Shape;
import flash.events.Event;
var easing:Number = .25; // inching coefficient
var sp:Shape = super.addChild(new Shape()) as Shape; // draw circle
sp.graphics.beginFill(0x0,.6);
sp.graphics.drawCircle(40,40,40);
sp.x = super.stage.stageWidth - sp.width >> 1;
sp.y = super.stage.stageHeight - sp.height >> 1;
super.stage.addEventListener(Event.ENTER_FRAME, update, false, 0, true);
function update(e:Event):void
{
var targetX:int = super.stage.mouseX - (sp.width >> 1);
var targetY:int = super.stage.mouseY - (sp.height >> 1);
sp.x += (targetX - sp.x) * easing;
sp.y += (targetY - sp.y) * easing;
}