Ext.onReady(function(){
    var win2;
		var button = Ext.get('show-btn3');
    showBtn3 = Ext.get('show-btn3');
     Ext.get('show-btn3').on('click', function(){  
        if(!win2){
            win2 = new Ext.Window({
                applyTo     : 'hello-win2',
                layout      : 'fit',
                width       : 540,
                height      : 290,
                x: 200,
                y: 140,
                closeAction :'hide',
                plain       : true,
                items       : new Ext.TabPanel({
                    applyTo        : 'hello-tabs2',
                    autoTabs       : true,
                    activeTab      : 0,
                    deferredRender : false,
                    border         : false
                }),

                buttons: [{
                    text     : 'Close',
                    handler  : function(){
                        win2.hide();
                    }
                }]
            });
        }
        win2.show(button);
    });
});