arpeggioBracket spanning multiple voices on a single staff?

[William Bajzek]

Hi all, a quick question (I hope). I would like to place a bracket on a guitar 
music staff, indicating a partial barre, as is frequently found in Frank 
Koonce's editions. \arpeggioBracket more or less does it, but only within a 
single voice. The following is a modified snippet from the documentation. My 
expectation and hope is that it would show the arpeggio bracket instead of the 
zigzag one, but it doesn't. Can this be done? 

\new Staff \with {
  \consists "Span_arpeggio_engraver"
}
\relative c' {
  \set Staff.connectArpeggios = ##t
  <<
    { \arpeggioBracket <e' g>4\arpeggio <d f> <d f>2 } \\
    { \arpeggioBracket <d, f>2\arpeggio <g b>2 }
  >>
}


Here is an example of what I would like:     
http://dl.dropbox.com/u/597433/barre.gif



- William Bajzek
please note my new email address: address@hidden