the only way i can get this to work is if i customise the timeout form as follows:
ahdtop.name = "";
alertmsg("Sorry,_your_session_has_timed_", msgtext("Press_OK_to_close_all_%1_windo", cfgProductName) );
// Sorry, your session has timed out.
// ahdtop.session_timeout("$prop.SID", window);
logout_all_windows(1);
surely i shouldn't need to do this?