public function updated_config($ui)
 {
     $ui->save();
     // if they selected an option other than manually, set up the cron
     $frequency = Options::get('exportsnapshot__frequency');
     // delete the crontab entry, if there is one
     CronTab::delete_cronjob('snapshot');
     switch ($frequency) {
         case 'manually':
             // do nothing
             break;
         case 'hourly':
             CronTab::add_hourly_cron('snapshot', array('ExportSnapshot', 'run'), _t('Hourly Export Snapshot', 'exportsnapshot'));
             break;
         case 'daily':
             CronTab::add_daily_cron('snapshot', array('ExportSnapshot', 'run'), _t('Daily Export Snapshot', 'exportsnapshot'));
             break;
         case 'weekly':
             CronTab::add_weekly_cron('snapshot', array('ExportSnapshot', 'run'), _t('Weekly Export Snapshot', 'exportsnapshot'));
             break;
         case 'monthly':
             CronTab::add_monthly_cron('snapshot', array('ExportSnapshot', 'run'), _t('Monthly Export Snapshot', 'exportsnapshot'));
             break;
     }
     return false;
 }