centrare punto di registrazione di un movieclip create via actionscript

[and80]

così

function disegnaBarra(target_mc:MovieClip, boxWidth:Number, boxHeight:Number, fillColor:Number, fillAlpha:Number):Void {
    with (target_mc) {
        beginFill(fillColor,fillAlpha);
        moveTo(-boxWidth/2,-boxHeight/2);
        lineTo(boxWidth/2,-boxHeight/2);
        lineTo(boxWidth/2,boxHeight/2);
        lineTo(-boxWidth/2,boxHeight/2);
        lineTo(-boxWidth/2,-boxHeight/2);
        endFill();
    }
}