title: Extjs4 Formatting date column in GridPanel
body: <p>Normally it works like this:  </p>
  
  <pre><code>{
     text:'title1',
     dataIndex: 'dataIndex1',
     renderer: Ext.util.Format.dateRenderer('d/m/Y')
  },
  </code></pre>
  
  <p>But in the renderer I have a function. Like this:  </p>
  
  <pre><code>{
                  text:'title1',
                  dataIndex: 'dataIndex1',
                  renderer: function(value, p, r)
                  {
                      my_store.clearFilter(true);
                      var index = my_store.findExact('cin',r.get('cin'));
                      var rec = my_store.getAt(index);
                      if(rec!=null)
                      {
                          return rec.get('dataIndex1')
                      }
                  }
              }  
  </code></pre>
  
  <p>So how to add <code>Ext.util.Format.dateRenderer('d/m/Y')</code> to the function?</p>