title: Fatal error: Call to undefined method JToolbarHelper::deleteListX() in joomla
body: <pre><code>protected function addToolBar() 
  {
      JToolBarHelper::title(JText::_('COM_HELLOWORLD_MANAGER_HELLOWORLDS'), 'helloworld');
      JToolBarHelper::deleteListX('', 'helloworlds.delete');
      JToolBarHelper::editListX('helloworld.edit');
      JToolBarHelper::addNewX('helloworld.add');
  }
  </code></pre>
  
  <p>what is the error in this syntax</p>