ActionScript3.0 キーボード

package{
  import flash.display.Sprite;
  import flash.text.TextField;
  import flash.events.KeyboardEvent;

[SWF(width="300", height="200", backgroundColor="0xFFFFFF")]

  public class Main extends Sprite
  {
    private var text_field:TextField;

    public function Main()
    {
      text_field = new TextField();
      text_field.x = 50;
      text_field.y = 50;
      text_field.width = 50;
      text_field.height = 50;

      addChild(text_field);

      stage.addEventListener(KeyboardEvent.KEY_DOWN, KeyDownFunc);
    }

    private function KeyDownFunc(event:KeyboardEvent):void
    {
      text_field.text = "" + event.keyCode;
    }
  }
}