glissandi and line breaks

[luis jure]

dear list,

i'm trying to resolve a tricky passage involving double stop glissandi
spanning several measures. i found a solution involving three different
voices. the difficult part is that due to music spacing, i need a line
break in middle of the glissando. this works well with parallel
glissandi (top staff in the attached example), but it doesn't look so
good with divergent glissandi (lower staff). it seems the glissando
line has no memory where it was before the line break. is there a way
to improve this? should i consider this a sort of "bug"? here's my
(dirty) code (a very simplified example of the real musical situation):



\version "2.11.50"

global = {
        \time 4/4
}


ViolinI = \new Voice \with {
        \remove Forbid_line_break_engraver
     }  {
        \time 4/4
        \relative c' {
        % c 1
        c'8 c c c c c c c
        c8 c c c c c c c
        c8 c c c c c
<<
        {
        \stemDown
        <g=''' a,>4
        % c 2
        \override NoteHead #'transparent = ##t d, d d d \break
        % c 3
        d \revert NoteHead #'transparent <d c'>4
        } 


        \new Voice \with {
        \remove Forbid_line_break_engraver }
        {
        \override Stem #'stencil = ##f
        \override NoteHead #'transparent = ##t
        \override Glissando #'breakable = ##t
        g='''4*6\glissando c,4
        }


        \new Voice \with {
        \remove Forbid_line_break_engraver }
        {
        \override Stem #'stencil = ##f
        \override NoteHead #'transparent = ##t
        \override Glissando #'breakable = ##t
        a=''4*6\glissando d,4
        }
>>
        c8 c c c 
        c8 c c c c c c c
        c8 c c c c c c c
        c8 c c c c c c c

}
}


ViolinII = \new Voice \with {
        \remove Forbid_line_break_engraver
     }  {
        \time 4/4
        \relative c' {
        % c 1
        c'8 c c c c c c c
        c8 c c c c c c c
        c8 c c c c 
<<
        {
        \stemDown
        g='''8 \once \override NoteHead #'transparent = ##t d, g='''8
        % c 2
        \override NoteHead #'transparent = ##t d,4 d d d
        % c 3
        d \revert NoteHead #'transparent <d c'>4
        } 


        \new Voice \with {
        \remove Forbid_line_break_engraver }
        {
        \override Stem #'stencil = ##f
        \override NoteHead #'transparent = ##t
        \override Glissando #'breakable = ##t
        g='''8*13\glissando d,4
        }


        \new Voice \with {
        \remove Forbid_line_break_engraver }
        {
        s4
        \override Stem #'stencil = ##f
        \override NoteHead #'transparent = ##t
        \override Glissando #'breakable = ##t
        g='''8*11\glissando c,4
        }
>>
        c,8 c c c 
        c8 c c c c c c c
        c8 c c c c c c c
        c8 c c c c c c c

}
}


\score {
  \new StaffGroup 
  <<
    \new Staff = "violin1" { << \global \ViolinI >> }
    \new Staff = "violin2" { << \global \ViolinII >> }
  >>
  \layout { }
}

gliss.png
Description: PNG image