public function render(Varien_Object $row)
 {
     $permissionIds = $row->getPermissionIds();
     $permissionArray = explode(',', $permissionIds);
     $permissionSource = Mage::getSingleton('webpos/source_adminhtml_permission')->getOptionArray();
     $permissionText = array();
     foreach ($permissionArray as $permission) {
         if (isset($permissionSource[$permission])) {
             $permissionText[] = $permissionSource[$permission];
         }
     }
     $result = implode(', ', $permissionText);
     echo $result;
 }