Paolo Prete wrote on 02.06.2024:
> How can I draw a vertical (or even diagonal) line independently positioned
> from the notes in the score, that can span across staves, as shown in the
> figure?
For drawing lines independently from notes I do not use Lilypond
directly but postscript. For this purpose I have added a few lines of
code right at the beginning in the definition of bookTitleMarkup like
this (drawing two small horizontal lines in the page margins):
--8<---------------cut here---------------start------------->8---
bookTitleMarkup = \markup {
\column {
\postscript #"
gsave
initmatrix
1 setlinewidth 0 306 moveto 6 0 rlineto stroke
1 setlinewidth 377 306 moveto 6 0 rlineto stroke
grestore"
\fill-line {
\fromproperty #'header:instrument
...
--8<---------------cut here---------------end--------------->8---
Don't know if it helps in your case, but maybe gives you an idea of how
to proceed.
Have fun
Torsten
