Perhaps I should add two drawbacks of my use of small notes with real
duration as 'gracenotes':
1. the gap between the notes is larger than it should be. Attempting
to narrow the gap with the \times construct
e.g.
\times 1/4 {c''16 e''} \times 15/16 {d''4}
doesn't significantly narrow the c'' e'' d'' gaps, it primarily
lengthens the gap after the d'';
2. other simultaneous notes line up with the (first) gracenote,
rather than with the main note as is wanted to show the music
structure properly.
An option with a single gracenote is to put the main & grace notes in
separate voices and use hshift, but hshift only moves things to the
right, not the left so again other notes line up with the gracenote.
Putting gracenote and mainnote in a chord can't work with more than
one gracenote, obviously, but it also doesn't work when even a single
gracenote is higher in pitch than the main note because the higher
pitch of a pair appears to the right of the stem. (It also doesn't
work currently because Lily applies properties to all notes of a
chord even when it is marked only for one note, but Han-Wen has this
in the TODO list to fix because I'll need it for the two note shapes
in Scarlatti.)
I suspect that the cleanest permanent solution might be similar to
the one I use, but with spacing and horizontal position corrected
along with the notehead size...
