It may be completely useless, and I can't verify it as no known samples
or other known/accessible software using it, but why not?
Putting this together with he 422 code requires making it slightly more
generic. I'm still staying with a "huge" if tree instead of a table to
select the scanline worker callback, because it's actually small and not
huge (although it not being generic still feels slightly painful).
wm4
320fa3bbe7