Some things that might be nice to have, in no particular order:
- Quick color palette, for switching between frequently-used colors.
- Custom dither pattern creation.
- Metadata support. The first screen hole is used for a mode byte and a signature, and the last screen hole is conventionally omitted, but that leaves 496 bytes of storage for modification dates, author identification, etc.
- The scribble tool should work with shaped brushes as well as single points.
- Rulers. The current version has grid lines to show pixel cells, with slight color variations for byte boundaries, but an optional ruler overlay could be more useful.
- Middle-out ellipse drawing. Filling rect bounds can be counterintuitive, though it does have the advantage of allowing even width/height, and doesn't require clipping.
- Provide a way to display black0/white0 different from black1/white1, perhaps an optional tint or overlay.
- Add a notion of background color, for "cut" operations.
- Do something clever with Martymations (see The Print Shop Color side B).
Some things that might be nice to have, in no particular order: