private function init():void {
     sprite1 = new Sprite();
     addChild(sprite1);
     sprite1.graphics.beginFill(0x000000);
     sprite1.graphics.drawRect(-2, -2, 4, 4);
     sprite1.graphics.endFill();
     sprite1.x = stage.stageWidth / 2;
     sprite1.y = stage.stageHeight / 2;
     
     textField = new TextField();
     addChild(textField);
     stage.addEventListener(MouseEvent.MOUSE_MOVE, onMouseMove);
    }