(head-up (ly:grob-array-ref heads 1))
(fraction (ly:grob-property grob 'length-fraction 0.7))
(max-gap (ly:grob-property grob 'maximum-gap 0.45))
- ; distance between noteheads:
+ ;; distance between noteheads:
(distance (- (interval-start (ly:grob-extent head-up common Y))
(interval-end (ly:grob-extent head-down common Y))))
(gap (* 0.5 distance (- 1 fraction))))