хм... может так попробовать? очень простой код

Код:
package {
import flash.display.Sprite;
import flash.events.Event;
import flash.geom.Point;
public class Test extends Sprite
{
public var p0:Point;
public var p1:Point;
public function Test()
{
stage.frameRate=3;
p0 = new Point (mouseX,mouseY);
p1 = new Point (mouseX,mouseY);
this.graphics.lineStyle(1);
this.graphics.moveTo(mouseX,mouseY);
this.addEventListener(Event.ENTER_FRAME,enterFrame);
}
public function enterFrame(e:Event):void
{
var p:Point = new Point (mouseX,mouseY);
if(p1.subtract(p).length<5)return void;
var t:Number = 1.5;
var control:Point = new Point(p0.x+(p1.x-p0.x)*t,p0.y+(p1.y-p0.y)*t);
this.graphics.curveTo(control.x,control.y,mouseX,mouseY);
p0 = control;
p1 = p;
}
}
}