テキストが出てくる

/**
 * Copyright _wonder ( http://wonderfl.net/user/_wonder )
 * MIT License ( http://www.opensource.org/licenses/mit-license.php )
 * Downloaded from: http://wonderfl.net/c/gMmG
 */

// forked from _wonder's テキストロールオーバー
package {
    import flash.display.Sprite;
    import flash.text.TextField;
    import flash.text.TextFieldAutoSize;
    import flash.text.TextFormat;
    import flash.utils.Timer;
    import flash.events.TimerEvent;
    
    public class MyTextField extends Sprite {
        
        public var fld:TextField;
        public var timer:Timer;
        public var msg:String = "OL湯煙殺人事件の謎";
        
        public function MyTextField() {
            fld = new TextField();
            fld.x = 50;
            fld.y = 50;
            fld.autoSize = TextFieldAutoSize.LEFT;
            fld.background = true;
            fld.backgroundColor = 0XFFFFFF;
            
            var tf:TextFormat = new TextFormat();
            tf.font = "_typewriter";
            tf.size = 18;
            fld.defaultTextFormat = tf;
            addChild(fld);
            
            fld.selectable = false;
            
            timer = new Timer(100, fld.length);
            timer.addEventListener(TimerEvent.TIMER, timerHandler);
            timer.start();
        }
        
        public function timerHandler(e:TimerEvent):void{
            var char:String = msg.charAt(timer.currentCount-1);
            fld.appendText(char);
        }
        
    }
}