Hi Ken,
I implemented the trill span; it was not intuitive to me to end the trill span on the following note, but it seems to work.
It's possible to add a little bit of syntactic sugar for this construction:
\version "2.22"
trillSpan =
#(define-music-function (mus) (ly:music?)
#{
<>\startTrillSpan
#mus
<>\stopTrillSpan
#})
\relative {
d''2
\trillSpan e4. d16 e
\trillSpan { fis4 g gis4. } a8
a2
}
Lukas
