Pemakaian Iframe pada Extjs

listeners : {  
 itemcontextmenu :  function( grid, record, item, index, event){
  event.stopEvent();
  var menu = Ext.create('Ext.menu.Menu',{
   items: [{
    text: 'Export to XLS',
    iconCls: 'export',
    disabled : false,
    handler: function() { 
     var tgl  = Ext.getCmp('tgl').rawValue,
      branch  = Ext.getCmp('branch_id').getValue(); 
      status  = Ext.getCmp('status').getValue();
     Ext.getBody().mask('Creating File, please wait...', 'x-mask-loading');
     Ext.getBody().createChild({
      tag: 'iframe',
      cls: 'x-hidden',
      onload: 'Ext.getBody().unmask(); var t = Ext.get(this); ',
      src: 'services/sms_monitoring_installasi/export?tgl='+tgl+'&branch='+branch+'&status='+status,
     });                               
    }
   }]
  });
  menu.showAt(event.xy);
 }
},