Comment #16 on issue 2707 by [email protected]: Patch: Midi volume fixes http://code.google.com/p/lilypond/issues/detail?id=2707
Actually, somewhat nicer hide =#(define-music-function (parser location grob m) ((string? *unspecified*) ly:music?)
#{ \tweak $grob #'stencil ##f #m #})
since one can then also optionally specify the grob to disappear.
I'll make a separate proposal/issue.
