Thanks again very much. I checked it out and it works perfectly!

Just for the record (or anybody who searches), this is what I did:

\version "2.15.36"

parenthArpeggio= {
   \once \override Arpeggio #'stencil = #(lambda (grob)
     (parenthesize-stencil (ly:arpeggio::print grob) 0.1 0.5 0.5 0.2))
   \once \override Arpeggio #'before-line-breaking = #(lambda (grob)
     (set! (ly:grob-property grob 'X-extent)
           (ly:stencil-extent (ly:grob-property grob 'stencil) X)))
}

parenthArpeggioDraft = {
   \parenthArpeggio
   \once \override Arpeggio #'color = #red
}

\relative c' {
   \repeat unfold 4 {
     <c g' e'>-\arpeggio
   }
\parenthArpeggio<cis dis fis gis cis dis gis>-\arpeggio
   <cis dis fis gis cis dis>-\arpeggio
   \parenthArpeggioDraft<cis dis fis gis cis>-\arpeggio
   <cis dis fis gis>-\arpeggio
}

Hope it helps somebody ...
Best
Urs

-------- Original-Nachricht --------
Betreff: Re: parenthesizing arpeggios
Datum: Sun, 22 Apr 2012 20:23:01 -0500
Von: David Nalesnik <david.nalesnik@gmai...>
An: Urs Liska <lists@ursl...>
Kopie (CC): Lilypond-User <lilypond-user@gnu....>



Hi again!


    Here's something that works for arpeggios.  The attached file is a
    bit large because I needed to include several functions from
    stencil.scm to draw the parentheses.


Oh, what ever was I thinking!  No need at all for all that duplicated
code...

This is all you need:

\version "2.15.36"

\relative c' {
   \override Arpeggio #'stencil = #(lambda (grob)
     (parenthesize-stencil (ly:arpeggio::print grob) 0.1 0.5 0.5 0.2))
   \override Arpeggio #'before-line-breaking = #(lambda (grob)
     (set! (ly:grob-property grob 'X-extent)
           (ly:stencil-extent (ly:grob-property grob 'stencil) X)))
   \repeat unfold 4 {
<c g' e'>-\arpeggio
   }
<cis dis fis gis cis dis gis>-\arpeggio
<cis dis fis gis cis dis>-\arpeggio
<cis dis fis gis cis>-\arpeggio
<cis dis fis gis>-\arpeggio
}

-David