NoteHead X-offset, conflict with ly:grob-relative-coordinate

[Paul Morris]

> I'm not top posting.

% All the notes should be moved to the right-hand 
% side of the stem by overriding their X-offset 
% property, but something about the "rel-coord" 
% variable that is set by "ly:grob-relative-coordinate" 
% prevents this from working as it should.  After 
% removing that variable it works fine. Setting 
% X-extent also does not work (this is commented 
% out below).

\version "2.16.1"  

CustomNoteHeads =
#(lambda (grob)
  (let* (
    (notecol (ly:grob-parent grob 0))
    (rel-coord (ly:grob-relative-coordinate grob notecol 0)))
    (set! (ly:grob-property grob 'X-offset) 1.251178 )

    ;; (set! (ly:grob-property grob 'X-extent) '(0 . 4) ))
)

\score {
  \new Staff
    \with { 
      \override NoteHead #'before-line-breaking = \CustomNoteHeads
    }
    { c' d' e' f' }
  \layout { }
}