Too high measure numbers with ossia staff

[Erika Pirnes]

Hi,

I just learned how to use the ossia staff. And I'm quite happy with the 
results, except it seems that the measure numbers follow the hidden ossia staff 
instead of the first visible staff. Can anyone think of a nice way to move the 
measure numbers down? Below is a modified version of the example in the 
documentation.

\version "2.18.2"

oss = \markup {\raise #1 "ossia" }

music = \relative c' {
    <<
      { c4 b c2 }
      \context Staff = "ossia" {
        \stopStaff s1
      }
    >>

    <<
      { e4 f e2 }
      \context Staff = "ossia" {
        \startStaff e4^\oss g8 f e2 \stopStaff
      }
    >>
    g4 a g2 \break
    c4 b c2
    <<
      { g4 a g2 }
      \context Staff = "ossia" {
        \startStaff g4^\oss e8 f g2 \stopStaff
      }
    >>
    e4 d c2
  }

\score{
<<
  \new Staff = "ossia" \with {
    \remove "Time_signature_engraver"
    \hide Clef
    fontSize = #-3
    \override StaffSymbol.staff-space = #(magstep -3)
    \override StaffSymbol.thickness = #(magstep -3)
  }
  \new Staff <<\music>>
>>
}


Thanks in advance!
Erika