/**
  * Returns sorting fields array
  *
  * @return array
  */
 public function getListSorting()
 {
     $aSort = oxConfig::getParameter('sort');
     if ($this->_aCurrSorting === null && isset($aSort[0]['oxorderdate'])) {
         $this->_aCurrSorting[]["max(oxorder.oxorderdate)"] = "desc";
         return $this->_aCurrSorting;
     } else {
         return parent::getListSorting();
     }
 }