title: Magento - Add functionality to my new added button
body: <p>I made a new button in adminhtml by extending *Mage_Adminhtml_Block_Sales_Order* and now i want to have some functionality in it. </p>
  
  <pre><code>    class Module_Parcel_Block_Adminhtml_Sales_Order extends Mage_Adminhtml_Block_Sales_Order 
      {
          public function  __construct() {
  
              $this-&gt;_addButton('Parcel Sync', array(
                  'label'     =&gt; Mage::helper('Sales')-&gt;__('Parcel Sync'),
                  'onclick'   =&gt; 'window.open(\'/magento/app/code/local/Module/Parcel/Controller/Sync.php\')',
                  'class'     =&gt; 'go'
              ), 0, 100, 'header', 'header');
  
              parent::__construct();
          }
      }
  </code></pre>
  
  <p>You can see here how i implement my button, the <strong>onclick</strong> function is wrong because i can not acces my controller like that. How do i solve this?</p>
  
  <p><strong>EDIT</strong> this is my controller</p>
  
  <pre><code>class Module_Parcel_IntegerController extends Mage_Core_Controller_Front_Action
  {
      public function multiplyAction()
      {
          echo 'Works';
      }
  }
  </code></pre>
  
  <p>Do i need to add this controller to config.xml to get this code working? (thx to magik)</p>
  
  <pre><code>Mage::helper('adminhtml')-&gt;getUrl("Module_Parcel/adminhtml_controller/sync"); 
  </code></pre>