Hello.
1) How can I associate a stencil to a NoteColumn grob?
I would like to show a vertical line in correspondence of it, but it seems that
\override NoteColumn.stencil ... has no effect.
2) is it possible to associate an output-attributes list to the NoteColumn grob, as well (so that it appears on the corresponding svg tag)?
I don't mean a property of the NoteHead, or Stem etc.: I mean a property of the NoteColumn (invisible) grob
Thanks,
Paolo