Consider this example ```tex \version "2.19.2"
music = { r4 r r \mark III r } { \music } { \override Score.RehearsalMark.non-musical = #'() \music } \layout { \context { \Score \override NonMusicalPaperColumn.stencil = #ly:paper-column::print \override PaperColumn.stencil = #ly:paper-column::print } } ``` Why does the `NonMusicalPaperColumn` grob have a width of 0.5 units? Where it is defined? And where does the additional 0.25 units between the rest and the non-musical paper column come from? Werner