\version "2.19.17"

#(define (remove-first symbol alist)
   (let loop ((alist alist) (result '()))
     (cond
      ((null? alist) result)
      ((eq? (caar alist) symbol) (append result (cdr alist)))
      (else (loop (cdr alist) (append result (car alist)))))))


#(define (grobs-with-stencils)
   (let loop ((all all-grob-descriptions) (result '()))
     (if (null? all)
         result
         (if (assoc-get 'stencil (cdar all))
             (loop (cdr all) (cons (caar all) result))
             (loop (cdr all) result)))))

#(define (mark-tweak grob)
   (let* ((default (assoc-get (grob::name grob) all-grob-descriptions))
          (after-line-return (assoc-get 'after-line-breaking default)) 
          (props (ly:grob-basic-properties grob))
          ;; Our procedure has been added to the head of grob's basic
          ;; properties.  Let's not count it as a tweak!
          (props
           (remove
            (lambda (p)
              (and (procedure? (cdr p))
                   (eq? (procedure-name (cdr p)) 'mark-tweak)))
            props))
          ;; Yuck.  We should remove the _last_ entry in the alist.  Good
          ;; enough for now.  Just don't override Clef.glyph.
          (props
           (if (eq? (grob::name grob) 'Clef)
               (remove-first 'glyph props)
               props))
          (diff (lset-difference eq? props default)))
     ;; Tweaks will not appear in the "basic properties" alist of our grob, but
     ;; we can find them through the music event which led to the grob.  This
     ;; is available through the stream-event which caused our grob.
     (if (null? diff)
         (let* ((cause (event-cause grob))
                (tweaks (and cause
                             (ly:music-property
                              (ly:event-property cause 'music-cause)
                              'tweaks))))
           (if (pair? tweaks)
               (set! (ly:grob-property grob 'color) red)))
         (set! (ly:grob-property grob 'color) green))
     
     ;; Return any default setting of after-line-breaking.
     after-line-return))


markAllAlteredGrobs =
#(define-music-function (parser location) ()
   (let loop ((grobs (grobs-with-stencils)))
     (if (null? grobs)
         #{ #}
         #{
           \override #(list 'Score (car grobs) 'after-line-breaking) = #mark-tweak
           #(loop (cdr grobs))
         #})))

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%


\displayMusic 
{ 
  \voiceOne
  c-"hi"-1 \clef "bass_8" c,
}

\layout {
  \context {
    \Score
    \markAllAlteredGrobs
  }
}