[kh99]

I hardly know anything about jquery, but as for th query to modify the table, I think you'd want:

$vbulletin->db->query(" 
    UPDATE `" . TABLE_PREFIX . "session` 
    SET idle = '1' 
    WHERE dbsessionhash = {$vbulletin->session['vars']['dbsessionhash']}
");

otherwise you'll set idle in all sessions to 1. Also, you can check the value by checking $vbulletin->session['vars']['idle'] so you don't have to do a query.