@verb #9359:"set_message_read" this none this rxdo #8084
@program #9359:"set_message_read" this none this
{message_id, who, ng} = args
caller_perms():controls(who) || raise(E_PERM)
mid = this:message_id(message_id, ng)
propname = " " + tostr(toint(who))
unread = `this.(propname) ! E_PROPNF => {}'
i = listiassoc(ng, unread)
if (!i)
  return
else
  unread[i] = setremove(unread[i], mid)
endif
"Remove just the {ng} if it exists."
unread = setremove(unread, {ng})
if (unread)
  this.(propname) = unread
else
  `delete_property(this, propname) ! E_PROPNF'
endif
"Last modified by Dax (#789) on Tue May  3 14:12:00 2005 MDT."
.