- SCM props = transpose_mutable (ev->get_property_alist (true), diff);
- ev = new Stream_event (ev->get_property ("class"), props);
- transposed_musics_ = scm_cons (ev->unprotect (), transposed_musics_);
+ SCM copy = ly_music_deep_copy (mus->self_scm ());
+ mus = unsmob_music (copy);
+
+ transposed_musics_ = scm_cons (copy, transposed_musics_);
+ mus->transpose (diff);