title: How to override refresh action in PagingToolbar
body: <p>I need to write some action based on the refresh button in the Paging toolbar. How can I override the <code>doRefresh()</code> method?</p>
  
  <pre><code>this.bbar=Ext.create('Ext.PagingToolbar', {
        store: store,
        displayInfo: true,
        displayMsg: 'Displaying records {0} - {1} of {2}',
        emptyMsg: "No topics to display" 
  });
  </code></pre>