/**
  * Create a template from the override file, else from the base file.
  *
  * @param string $tpl_name filename
  * @return Smarty_Internal_Template
  */
 public function createTemplate($tpl_name)
 {
     $this->context->smarty->assign(array('tpl_dir' => $this->tpl_dir));
     return parent::createTemplate($tpl_name);
 }