\version "2.12.2"

\header {
  texidoc = "
Since the staves in a PianoStaff context no longer have a fixed
distance set as default, this can result in wide variations in system
spacing.If you need to prevent the spacing engine from varying the
distance between staves (not just piano staves), you can override the
property @code{line-break-system-details} in the
@code{NonMusicalPaperColumn} object. In the first example, we override
the @code{NonMusicalPaperColumn} object in the score's context block;
the result is completely fixed vertical distance throughout the score.
In the second example, the override is applied on the fly at different
points (but always at line breaks) throughout the score; the result is
precisely controlled -- but varying -- amounts of vertical space for
each system, plus the option (see final system) of swapping the staves
around. Note that in this case, overriding @code{NonMusicalPaperColumn}
inline with note entry requires the special @code{\\overrideProperty}
command.



"
  doctitle = "Forcing fixed distance between staves"
}
\book {
  \score {
    \new PianoStaff <<
      \new Staff {
        c'1^"Fixed distance: fourteen staff spaces for every system"
        \break
        \repeat unfold 5 { c'1 \break }
      }
      \new Staff {
        \clef bass
        \repeat unfold 6 { c'1 }
      }
    >>
    \layout {
      \context {
        \Score
        \override NonMusicalPaperColumn
          #'line-break-system-details = #'((alignment-offsets . (0 -14)))
      }
    }
  }
  
  \score {
    \new StaffGroup <<
      \new Staff {
        \overrideProperty #"Score.NonMusicalPaperColumn"
          #'line-break-system-details #'((alignment-offsets . (0 -10)))
        c'1^"Ten staff spaces"
        \break
        \overrideProperty #"Score.NonMusicalPaperColumn"
          #'line-break-system-details #'((alignment-offsets . (0 -20)))
        c'1^"Twenty staff spaces"
        \break
        \overrideProperty #"Score.NonMusicalPaperColumn"
          #'line-break-system-details #'((alignment-offsets . (0 -30)))
        c'1^"Thirty staff spaces"
        \break
        \overrideProperty #"Score.NonMusicalPaperColumn"
          #'line-break-system-details #'((alignment-offsets . (0 10)))
        c'1^"Ten staff spaces again, with staves swapped around"
      }
      \new Staff {
        \clef bass
        c'1
        c'1
        c'1
        c'1
      }
    >>
  }
}