What determines whether the down-mod is enabled?
pg:     (def canvote (user i dir)
      (and user
           (news-type i)
           (live i)
           (or (is dir 'up) (> i!score lowest-score*))
           (no ((votes user) i!id))
           (or (is dir 'up)
               (and (acomment i)
                    (> (karma user) downvote-threshold*)
                    (no (aand i!parent (author user (item it))))))))