title: Magento Backend Product list grid
body: <p>Does anyone know how to add a field containing an input type text element or a dropdown element to a magento backend product list grid?
  I managed to add a new column to my custom module backend product listing grid like this:</p>
  
  <pre><code>$this-&gt;addColumn('blabla', array(
          'header'  =&gt; Mage::helper('customer')-&gt;__('On Hold?'),
          'width'   =&gt; '120',
          'index'   =&gt; 'bla',
          'type'    =&gt; 'options',
          'options' =&gt; array('1' =&gt; 'Yes', '0' =&gt; 'No')
  ));
  </code></pre>
  
  <p>but this command only adds the dropdown to my grid header, while i need the dropdown to appear in the left side of every product listed on that grid (just like the checkbox appears when you go for instance in backend on a product edit page and you select related products, or upsell products)</p>