Issue 1657 in lilypond: Balloon fails with cross-staff arpeggios

[lilypond]

Status: Accepted
Owner: ----
Labels: Type-Defect Priority-Low

New issue 1657 by address@hidden: Balloon fails with cross-staff  
arpeggios
http://code.google.com/p/lilypond/issues/detail?id=1657

\version "2.15"
\new PianoStaff \with { \consists "Balloon_engraver" } <<
 \set PianoStaff.connectArpeggios = ##t
 { \balloonGrobText #'Arpeggio #'(-0.1 . 0) \markup "G.O." \repeat unfold 5
a''\arpeggio }
 { \repeat unfold 5 a\arpeggio } >>

I've confirmed this as written with 2,12,3, 2.13.61 and 2.15.0.
I've also discovered that setting \balloonLengthOn hels the collision with  
the time signature. The bigger change comes from removing Balloon_engraver  
from the PianoStaff and putting it into explicitley declared Voices.  This  
gives a partial balloon in the upper voice and a complete but probably  
wrongly-sized one in the lower.