issue 3418 is more serious than we can imagine

[Karol Majewski]

It seems that the difference in horizontal spacing is very small, but when
the line is stretched, it becomes huge!

\version "2.17.95"

\paper {
  ragged-right = ##f
}

ss = \markup \translate #'(1.28 . -0) {
  \override #'(thickness . 1.5)
  \translate #'(0 . -0.3)
  \draw-line #'(6 . 0)
}

{
  f'4^\ss f'4 f'4^\ss \new Voice { f'4 }
  f'4^\ss f'4 f'4^\ss \new Voice { f'4 }
  f'4^\ss f'4 f'4^\ss \new Voice { f'4 }
}

ht.png
Description: PNG image