\version "2.13.0"
\pointAndClickOff

#(define (move-left grob)
  (let* ((line-thickness (ly:staff-symbol-line-thickness grob))
         (default-stem-thickness (* 1.3 line-thickness))
         (X-extent (ly:stencil-extent (ly:note-head::print grob) 0))
         (width (- (cdr X-extent) (car X-extent)))
         (offset (if (< 0 (ly:grob-property grob 'duration-log))
                     (- (/ default-stem-thickness 2) width)
                     (- (* default-stem-thickness 2) width))))
    offset))

#(define (move-right grob)
  (let* ((line-thickness (ly:staff-symbol-line-thickness grob))
         (default-stem-thickness (* 1.3 line-thickness))
         (X-extent (ly:stencil-extent (ly:note-head::print grob) 0))
         (width (- (cdr X-extent) (car X-extent)))
         (offset (if (< 0 (ly:grob-property grob 'duration-log))
                     (- width (/ default-stem-thickness 2))
                     (- width (* default-stem-thickness 2)))))
    offset))

\relative {
  % adjust Stem 'length and 'extra-offset if
  % the second is at one end of the stem:
  \once \override Stem #'length = #7.85
  \once \override Stem #'extra-offset = #'(0.065 . -0.45)
  <\tweak #'X-offset #move-right d
   \tweak #'X-offset #move-left e
   gis>4

  \once \override Stem #'length = #7.85
  \once \override Stem #'extra-offset = #'(0.065 . -0.45)
  <\tweak #'X-offset #move-right d
   \tweak #'X-offset #move-left e
   gis>2

  % for some reason, it won't work unless you input the tweak first:
  <\tweak #'X-offset #move-left b'
   \tweak #'X-offset #move-right a
   e>4

  % ie. this doesn't work:
  % <e
  %  \tweak #'X-offset #move-right a
  %  \tweak #'X-offset #move-left b>4

  <\tweak #'X-offset #move-left b
   \tweak #'X-offset #move-right a e>1
}