David’s interpretation of my idea isn’t correct. I never suggested letting the
second Staff start after the grace note, simply that decisions for that Staff
should be made independently of the Staff that contains the grace music.
Here’s a set of rules that handles this issue without a problem that I can see:
1. Determine which contexts are affected by G.
2a. Determine all grobs and events (e.g. overrides) in each Staff that aren’t
affected by G.
2b. Split non-affected contexts into pre-G and post-G portions.
3a. Determine all grobs and events (e.g., overrides) in each Staff affected by
G.
3b. Split affected contexts into pre-G, G, and post-G portions.
4. Determine spacing, taking into account all portions as determined above.
So in this “clef at the beginning” example, my rules map to logic as follows:
1. Upper staff is affected by G; lower staff isn’t.
2a. Lower staff should include: bass clef, time signature, and note.
2b. Bass clef and time signature are pre-G; note [and any note-attached
zero-duration events!] is post-G.
3a. Upper staff should include: treble clef, time signature, grace note, and
note.
3b. Treble clef and time signature are pre-G; grace note is G; note is post-G
4. Proceed as per normal spacing rules.