Cross-staff tie interferes with staff spacing

[DJF]

I’ve got a cross-staff tie in an organ piece which appears to be responsible 
for adding unwanted space between the L.H. staff and the Pedal staff. If I 
comment out the \shape line, the spacing then conforms as expected, using the 
values in the second VerticalAxisGroup block, but then the tie goes way up 
above the R.H. staff. 

There are a few programming errors in the log: “My pure_y_common is a 
VerticalAlignment, which might contain several staves” and “Some of my 
vertical-skyline-elements are outside my VerticalAxisGroup”.

I have a suspicion that I may be going about this (staff spacing) in a way 
which is not ideal, but it’s what I’ve been using and it largely works. I’ll 
happily take any comments on that, but my primary concern at present is getting 
the tie in the right place, and, at the same time, having the proper spacing to 
the Pedal staff. I’d be grateful for any advice.

-- Dan



\version "2.19.58"

rightOne = \relative c' {
   <c a'>4 g' fis 
}

leftOne = \relative c {
  \shape #'((-0.8 . -12.0) (-0.8 . -11.0) (-1.9 . -10.0) (-0.7 . -7.0)) Tie
  <e a~> \change Staff = "right" \stemDown a2 
}

pedal = \relative c {
  a4 b2 
}

\score {
  <<
    \new PianoStaff \with { \remove "Vertical_align_engraver" } % removes extra 
space before pedal staff
    <<
      \new Staff = "right" \with  { 
        \override VerticalAxisGroup.default-staff-staff-spacing =
    #'((basic-distance . 12.3)
       (minimum-distance . 9)
       (padding . 1)
       (stretchability . 15)) } % section above controls spacing between hands
      { \rightOne }
 
    \new Staff = "left" \with  {  
        \override VerticalAxisGroup.default-staff-staff-spacing =
    #'((basic-distance . 9.5)
       (minimum-distance . 7.0)
       (padding . 0)
       (stretchability . 0)) } % section above controls spacing between LH and 
pedal
    { \clef bass \leftOne }
    >>
      \new Staff = "pedal" { \clef bass \pedal }
  >>
}