[Sidenote: as long as we're on the topic, 2.7.19 introduces a really
wonderful bit of improved syntax over, say, 2.7.10. Previously, to
change rehearsal mark alignment, you had to use the following pair of
lines ...
%%%%% BEGIN 2.7.10 SNIPPET %%%%%
\override RehearsalMark #'self-alignment-X = #left
\override RehearsalMark #'X-offset-callbacks =
#`(,Self_alignment_interface::aligned_on_self)
%%%%% END 2.7.10 SNIPPET %%%%%%
... whereas now all you have to use is the first of the two lines,
which is a VERY nice improvement imo!]