The following problems have not been fixed at the time of this release:

1- Stream concatenation using [< ... >] does not always preserve the
   sharing among streams, and sometimes duplicate stream subcomponents.
   For instance, if you define s' = [< '1; s >] and then read alternatively
   from s' and from s, a given element of s can be read twice.
   The problem occurs only if s is in tail position inside s'.
   To guarantee proper sharing, move s in non-tail position, e.g.
   take s' = [< '1; s; [<>] >].

2- (macintosh) The graphics window does not work with monitors set to
   more than 256 colors.