Mailing list is dead (archive still available). Reported by Chris
Mask out colors from 'attr' in wchgat(). After Bill Gray.
Checking for WT_SESSION is unreliable; alternate method suggested by
Suppress warnings about sprintf().
8 colors for OS/2 full-screen. To Do: Hardware blinking?
Ad hoc test for windowed vs. full-screen VIO (OS/2) session, since they
ACS_BLOCK is poorly supported (at least as a cell-filling block).
Yes, it still works