The source code

    Ext.onReady(function(){
        var win;
        var button = Ext.get('show-btn');

        button.on('click', function(){
            // create the window on the first click and reuse on subsequent clicks
            if(!win){
                win = new Ext.Window({
                    applyTo:'hello-win',
                    layout:'fit',
                    width:500,
                    height:300,
                    closeAction:'hide',
                    plain: true,

                    items: new Ext.TabPanel({
                        applyTo: 'hello-tabs',
                        autoTabs:true,
                        activeTab:0,
                        deferredRender:false,
                        border:false
                    }),

                    buttons: [{
                        text:'Submit',
                        disabled:true
                    },{
                        text: 'Close',
                        handler: function(){
                            win.hide();
                        }
                    }]
                });
            }
            win.show(this);
        });
    });