\version "2.19.20"
#(ly:set-option 'point-and-click #f)
\paper { #(set-paper-size "a7") line-width = 50 }
\header { tagline = ##f }

mus = {
  \key ges \major
  d' des''
}

\layout {
  \context {
    \Staff
    \consists "Ambitus_engraver"
  }
}

\markup {
  \vspace #3
  \fill-line { "current default" }
}

\mus

\markup \fill-line { suggestion }

\score {
  \mus
  \layout {
    \context {
      \Score
      \override BreakAlignment.break-align-orders =
      #'#((left-edge
           cue-end-clef
           breathing-sign
           clef
           cue-clef
           staff-bar
           key-cancellation
           key-signature
           ambitus
           time-signature
           custos)
          (left-edge
           cue-end-clef
           breathing-sign
           clef
           cue-clef
           staff-bar
           key-cancellation
           key-signature
           ambitus
           time-signature
           custos)
          (left-edge
           breathing-sign
           clef
           key-cancellation
           key-signature
           ambitus
           time-signature
           staff-bar
           cue-clef
           custos))
    }
    \context {
      \Staff
      \override KeySignature.space-alist =
      #'((ambitus extra-space . 1)
         (time-signature extra-space . 1.15)
         (staff-bar extra-space . 1.1)
         (cue-clef extra-space . 0.5)
         (custos extra-space . 0.5)
         (right-edge extra-space . 0.5)
         (first-note fixed-space . 2.5))
      \override Ambitus.space-alist =
      #'((time-signature extra-space . 1.15)
         (staff-bar extra-space . 1.1)
         (cue-clef extra-space . 0.5)
         (custos extra-space . 0.5)
         (right-edge extra-space . 0.5)
         (first-note fixed-space . 2.5))
      \override Clef.space-alist =
      #'((cue-clef extra-space . 2.0)
         (staff-bar extra-space . 0.7)
         (ambitus extra-space . 1)
         (key-cancellation minimum-space . 3.5)
         (key-signature minimum-space . 3.5)
         (time-signature minimum-space . 4.2)
         (first-note minimum-fixed-space . 5.0)
         (next-note extra-space . 1.0)
         (right-edge extra-space . 0.5))
    }
  }
}