A short web article by Ralph Griswold on using program visualization, the technique of displaying a running program's activity as evolving images, as a source for weave drafts. It explains how a program's event sequences can be split into type and value sequences and mapped to threading and treadling (types) and color (values). It also covers practical problems: sequences that are too long, runs of identical events, and too many distinct values. It includes a page of program visualization snapshots and a final page showing a draft-like colored pattern derived from a chess-playing program.