Message Icons for Message Box from code behind and in Java script

[Dorababu]

Is it possible to add required icon for message box from code behind

X.MessageBox.Alert("Click", chk).Show(); for this I have to add an ICON

In the script

<script type="text/javascript">
         var onBeforeSubmit = function (radioGroup) {
             if (Ext.isEmptyObj(radioGroup.getValue())) {
                 Ext.Msg.alert("Error", "Select an item.");  // Here I would like to add an ICON
                 return false;
             }
         };
   </script>