Thanks a lot, David. It works as advertised. I do think I read about this somewhere in the manuals, but I couldn't find it.
This uses really involved code to simulate something that does not
really map well to LilyPond's internals so it may interfere with other tricky code.
I'm pretty sure that I'm not at the level of skill to be writing other tricky code, so no problem :-)
For the benefit of anyone on the list who might find this useful, here's the simple function I'm using this in. It adds falling gliss lines à la sliding falls commonly notated in rock guitar music, and it's probably not a good implementation, but it works as I'd like it to:
fall = #(define-music-function (input) (ly:music?)
(make-relative (input)
input
#{
\afterGrace 16/16
<< $input <>\glissando >>
\transpose c g, {
\once \omit Flag
\once \override Stem.length = #0
\once \override NoteHead.font-size = #-50
\once \hideNotes
$input
}
#}))
Thanks,
Randy