GeoExt form and file upload
<p>I have a GeoExt form and want to do file upload here. But i never work with GeoEXT. I have this.</p>

<pre><code>buttons: [{
  text: 'Загрузить',
  handler: function(){
  if(fp.getForm().isValid() &amp;&amp; Ext.getCmp('opinions').getValue()=="blabla"){
    form_action=1;
    fp.getForm().submit({
             url: '&lt;portlet: actionURL&gt;',
             waitMsg: 'WAITING...',
     success: function(fp, o) {
              DO SOMETHING
              }
             }
            }
          }]
</code></pre>

<p>This is correct?<br>
What arguments use in  <code>success: function(fp, o)</code>? First argument is <code>FormPanel</code> but i dont understand what is second.
Another question how to do asynchronous file upload in this case? </p>
