Thanks a lot for your help Danguba. I also have a text box and enter button on UI and based on value entered in text box, I need to refresh contents of 3rd tab. Below is my code:

{//second tab end, third tab starts
id: 'test',
title: "Test3",
layout: "fit",
html: iframebody,
listeners: {
'render': function()

'show': function(panel){
//var tickerValue1 = Ext.getCmp('tabpanel').getActiveTab().html;
theurl = '' +ticker+';
iframebody = '<iframe width=100% height=100% src='+theurl+'></iframe>';
var tab1= Ext.getCmp('tabpanel').setActiveTab(2);
},//show listener ended

Now, when I press enter, tab doesnt get refreshed with new ticker even though the alert message shows updated html for the tab. Any help would be highly appreciated.