Hi Jean,
> Just take the example I gave earlier and remove the grace skips.
>
> \version "2.24.0"
> <<
> \new Staff { \grace { c'8 d'8 } c'1 }
> \new Staff {
> \once \override Staff.TimeSignature.color = "red"
> \once \override NoteHead.color = "red"
> c'1
> }
> >>
> Do the overrides occur before the graces?
No: “obviously” (to me), all \once \override or \tweak commands are attached to
the moment they occur in, not to some “liminal space” created by another
context. This example doesn’t convince me: I can still easily find a single
rule that covers this case [as I understand it] and the alternative [given
clear documentation/instructions on how to apply the override before the grace
music].
In my mind, grace time exists like the dialogue over a barline-with-fermata in
a musical or opera: If you say that the downbeat of the next measure is spoken
by Frank, that doesn’t retroactively change the dialogue over the barline to be
spoken by Frank. (It's a twisted analogy, but it’s essentially what you’re
suggesting.)
Cheers,
Kieren.
