Simple drag and drop problem in AS 2

Hi

I have used the following tutorial to create a drap and drop game…

http://www.monkeyflash.com/flash/drag-and-drop-2/

Source file can be downloaded here:

http://www.monkeyflash.com/files/dragdrop2.zip

I need the objects to snap into the center of the targets upon release, how do I do that?
I have tried but my lack flash experience is a problem…


var counter:Number = 0;
var woodSound:Sound = new Sound();
woodSound.attachSound("woodblock");

onEnterFrame = function():Void{
    if(counter == 4){
        reply_txt.text = "Congrats, you're finished!";
    }
};


square_mc.onPress = function():Void {
    this.startDrag(true);
    reply_txt.text = "";
    this.swapDepths(this.getNextHighestDepth());
    xstart = this._x;
    ystart = this._y;
};
square_mc.onRelease = function():Void {
    this.stopDrag();
    if (eval(this._droptarget) == squareTarget_mc) {
        reply_txt.text="You got it!";
        this.enabled = false;
        counter++;
        woodSound.start(0,1);
    }
    else{
        reply_txt.text="No, keep trying!";
        this._x = xstart;
        this._y = ystart;
    }
};

Thank you very much…

-Bonwhis