private function SaveMemberGroups()
    {
        $selectedIDs = Request::PostArray('MemberGroup');
        if ($this->page->GetGuestsOnly())
        {
            $selectedIDs = array();
        }
        $exIDs = Membergroup::GetKeyList(MembergroupUtil::PageMembergroups($this->page));
        $this->DeleteOldMemberGroups($selectedIDs);
        $this->SaveNewMemberGroups($selectedIDs, $exIDs);
    }