/**
  * Append a 'disabled' CSS class to GridField rows whose WorkflowInstance records are not viewable/editable
  * by the current user. 
  * 
  * This is used to visually "grey out" records and it's leveraged in some overriding JavaScript, to maintain an ability
  * to click the target object's hyperlink.
  *
  * @param GridField $gridField
  * @param DataObject $record
  * @param string $columnName
  * @return array
  */
 public function getColumnAttributes($gridField, $record, $columnName)
 {
     $defaultAtts = array('class' => 'col-buttons');
     if ($record instanceof WorkflowInstance) {
         $isAdmin = Permission::check('ADMIN');
         $isAssigned = $record->getAssignedMembers()->find('ID', Member::currentUserID());
         if (!$isAdmin && !$isAssigned) {
             $atts['class'] = $defaultAtts['class'] . ' disabled';
             return $atts;
         }
         return $defaultAtts;
     }
     return $defaultAtts;
 }