title: add js/css file to admin product grid using xml
body: <p>i am trying to add some js and css files on admin product grid using xml, but i am not able to add the files,i tried an alternative, check below</p>
  
  <pre><code>protected function _prepareLayout()
  {
      $this-&gt;getLayout()-&gt;getBlock('head')-&gt;addJs('category_filter/lightbox.js');
      $this-&gt;getLayout()-&gt;getBlock('head')-&gt;addJs('category_filter/cat_filter.js');
  
      return parent::_prepareLayout();
  }
  </code></pre>
  
  <p>But instead of using this code i want to add the files using xml can any one suggest me how to add those files</p>