> [...] However, there is still some horizontal space between the note
> heads. What is it? I tried hard to find something in the IR but
> wasn't successful...
If I set `packed_spacing`, it's getting a little bit tighter, but
there is still horizontal whitespace between the note heads, and I
still don't know where it comes from.
Werner
======================================================================
```tex
\version "2.25.9"
#(set-global-staff-size 26)
{
\override Staff.Clef.show-horizontal-skylines = ##t
\override Staff.KeySignature.show-horizontal-skylines = ##t
\override Staff.TimeSignature.show-horizontal-skylines = ##t
\override NoteHead.show-horizontal-skylines = ##t
\override Score.SpacingSpanner.shortest-duration-space = 0
\override Score.SpacingSpanner.packed-spacing = ##t
\override Staff.KeySignature.extra-spacing-width = #'(0 . 0)
\override Staff.TimeSignature.extra-spacing-width = #'(0 . 0)
\override Staff.LeftEdge.space-alist.clef = #'(extra-space . 0)
\override Staff.Clef.space-alist.key-signature = #'(extra-space . 0)
\override Staff.KeySignature.space-alist.time-signature = #'(extra-space . 0)
\override Staff.KeySignature.space-alist.first-note = #'(fixed-space . 0)
\override Staff.TimeSignature.space-alist.first-note = #'(fixed-space . 0)
\key cis \major
bis'8 bis' bis' bis'
}
```
