title: When ever app does ajax request i want to add load mask
body: <p>In my sencha application, When ever app does ajax request i want to add load mask and after request complete i need to remove load mask.</p>
  
  <p>I tried below code but, its not working for me</p>
  
  <pre><code>var mask = new Ext.LoadMask(Ext.getBody(), {msg:"Loading..."});
  
     Ext.Ajax.on('beforerequest', function(){
          mask.show();
     });
  
     Ext.Ajax.on('requestcomplete', function(){
          mask.hide();
     });
  </code></pre>