Development Flash ActionScript

package{
    import flash.text.TextField;
    import flash.events.*;
    import flash.display.Sprite;
    public class FocusIn extends Sprite{
        var primaryText:TextField;
        var secondaryText:TextField;
        public function FocusIn(){
            primaryText = new TextField();
            secondaryText = new TextField();
            primaryText.text = "This is the primary TextField.";
            secondaryText.text = "This is the secondary TextField";
            primaryText.addEventListener(FocusEvent.FOCUS_IN, setFocus);
            secondaryText.addEventListener(FocusEvent.FOCUS_IN, setFocus);
            primaryText.addEventListener(FocusEvent.FOCUS_OUT, loseFocus);
            secondaryText.addEventListener(FocusEvent.FOCUS_OUT, loseFocus);
            primaryText.background = true;
            secondaryText.background = true;
            primaryText.backgroundColor = 0xFFFFFF;
            secondaryText.backgroundColor = 0xFFFFFF;
            addChild(this.primaryText);
            addChild(this.secondaryText);
            secondaryText.x = 500;
        }
        private function setFocus(focus:FocusEvent):void
        {
            (focus.target as TextField).backgroundColor = 0xFF0000;
        }
        private function loseFocus(focus:FocusEvent):void
        {
            (focus.target as TextField).backgroundColor = 0xFFFFFF;
        }
    }
}