0.18 (15 May 2001):
  Added support for deferred updates of filer windows
0.19 (16 May 2001):
  Added support for GBPB.
0.20 (16 May 2001):
  Fix for error handling on upcalls
0.21 (16 May 2001):
  Added option to only issue upcalls on callbacks
0.22 (16 May 2001):
  Removed user-mode protection from dynamic area
0.23 (25 Feb 2002):
  Updated to use new style makefiles.
  Updated to read DA name from Messages file.
