title: how to add extra filter to custom product reports in magento
body: <p>I am doing custom product reports in magento. I followed as the steps in the <a href="http://wrightcreativelabs.com/create-a-custom-magento-report-product-skus-in-new-orders/#comment-291" rel="nofollow">url</a></p>
  
  <p>But how can I add extra filter after "from:","to:","show By:". I know where to edit in core file(adminhtml/default/default/template/report/grid.php). But it is not the correct way. how to override this filter block for custom reports.</p>