Configurable offline time

I think it's very handy when the offline time is configurable. With offline time, I mean the time after a user is marked as offline.

The time of 15 minutes is too long in many situations. I need this feature for the QTChat module.

Please make the online/offline time configurable.

To use as an example for times:

/**
 * Help function. Provides online time options.
 *
 * @return array
 *   An associative array contains the time options.
 */
function _qtc_admin_online_time_options() {
  return array(
    300 => '5 '. t('minutes'),
    450 => '7 '. t('minutes'),
    600 => '10 '. t('minutes'),
    900 => '15 '. t('minutes'),
    1050 => '17 '. t('minutes'),
    1200 => '20 '. t('minutes'),
  );
}

I use the configurable offline time in the QTChat module (upcoming feature). But, is used a different time than 15 minutes there are differences in the times of User Stats. This produces confusion among users.

Thanks for the User stats module.