public function SavePreference($UserID, $Preference, $Value = '') {
      // Make sure that changes to the current user become effective immediately.
      $Session = Gdn::Session();
      if ($UserID == $Session->UserID)
         $Session->SetPreference($Preference, $Value, FALSE);

      return $this->SaveToSerializedColumn('Preferences', $UserID, $Preference, $Value);
   }