Drawings wrote a Color into field 2 for 3.2.3 and the ARGB value into a
mirror field. 4.6.3 writes the ARGB value into field 2 and reads either,
so nothing was lost, but the rollback test's byte-for-byte claim
compared this build's drawing writers against themselves. Drawings now
write 4.6.3's record too, the rollback registry swaps in 4.6.3's drawing
adapters, and the color test is the one 4.6.3 ships.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>