title: Call a method on close of msg box - extjs
body: <p>I have a custom message box; below is the code for it.  </p>
  
  <pre><code>var myMasks = new Ext.LoadMask(Ext.getCmp('salesFrm').el, {useMsg: false});
  myMasks.show();
  var msg = Ext.Msg.show( {                   
      msg:'&lt;br&gt;&lt;br&gt;&amp;emsp;&amp;emsp;&amp;emsp;&amp;emsp;&amp;emsp;&amp;emsp;'+'Enter Valid Quantity',
      buttons: Ext.Msg.OK,
      modal: false,
      closable: true,
      draggable: true,
      animEl: 'mb7',
      y:10,
      cls: 'msgbox',
      fn: function(btn){
          if(btn == 'ok'){            
          myMasks.hide();
      } 
  }
  });
  </code></pre>
  
  <p>On click of the 'OK' button, the mask on the underlying panel is hidden.<br>
  The same <strong>doesn't</strong> happen on click of the 'close' button at the right corner.<br>
  I tried searching for writing any handler method for the same but couldn't do so successfully. </p>
  
  <p>Can anyone help me out on how to hide the mask on the underlying panel on click of the 'close' button?</p>