"I've ported parts of asinshesq's MOD View or mark unread posts. The extension needs to modify the SQL query which fetches the unread topics data in the function get_unread_topics() in /includes/functions.php, right after the $sql_array variable is assembled (in 3.1.2 after line 1692)."

Event request from forum topic http://area51.phpbb.com/phpBB/viewtopic.php?f=111&t=46761