Dynamic Text Box in Flex

<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"

initialize="application1_creationCompleteHandler(event)" xmlns:s="library://ns.adobe.com/flex/spark" xmlns:mx1="library://ns.adobe.com/flex/mx">


<mx:Script>
<![CDATA[
import mx.events.FlexEvent;


protected function application1_creationCompleteHandler(event:FlexEvent):void
{
var txt:txtbox=new txtbox();
app_Vbx.addChild(txt);
}
]]>
</mx:Script>
<mx1:VBox id="app_Vbx" height="100%" width="100%">

</mx1:VBox>
</mx:Application>

package

{

import mx.containers.HBox;

import mx.containers.VBox;

import mx.controls.Alert;

import mx.controls.Label;

import mx.controls.TextInput;

import spark.components.HGroup;

import spark.components.VGroup;

public class txtbox extends VGroup

{

public function txtbox()

{

super();

this.percentHeight = 100;

this.percentWidth = 100;

Alert.show("txtbox" );

}

override protected function createChildren():void

{

Alert.show("text" );

var hbx:HGroup = new HGroup();

var txt1:TextInput = new TextInput();

txt1.percentHeight = 75;

txt1.percentWidth = 75;

var txt2:TextInput = new TextInput();

var txt3:TextInput = new TextInput();

var lbl:Label = new Label();

lbl.text="Sample";

hbx.height = 500;

hbx.width = 500;

hbx.addElement(lbl);

hbx.addElement(txt1);

hbx.addElement(txt2);

hbx.addElement(txt3);

addElement(hbx);

}

}

}