title: How do I define the target for _addButton?
body: <p>How do I define the target for _addButton? Below is the code I am using. I read the Magento docs located here but they didn't have this info: <a href="http://docs.magentocommerce.com/Mage_Adminhtml/Mage_Adminhtml_Block_Widget_Container.html#method_addButton" rel="nofollow">http://docs.magentocommerce.com/Mage_Adminhtml/Mage_Adminhtml_Block_Widget_Container.html#method_addButton</a></p>
  
  <pre><code> $this-&gt;_addButton('rebuild_files', array(
      'label'     =&gt; Mage::helper('core')-&gt;__('Rebuild Special Cache'),
      'onclick'   =&gt; 'setLocation(\'http://mysite.com/page/\')',
      'class'     =&gt; 'rebuild',
  )); 
  </code></pre>