Problems defining a BraceStaff

[John Zaitseff]

Dear LilyPond users,

I have searched the LilyPond documentation, lilypond-user mailing list 
archives and the LilyPond snippet repository---all without success...

The question is: how do I define a BraceStaff that is exactly like a 
ChoirStaff, except that braces are used instead of brackets at the start of 
systems?  In particular, I tried to define the following in my stylesheet 
(which gets included into all my documents):

  \layout {
      \context {
          \type "Engraver_group"
          \name "BraceStaff"
          \alias "ChoirStaff"

          \description
            "Just like @code{ChoirStaff} but with a brace (SystemStartBrace)
             instead of a bracket (SystemStartBraclet) at the start of
             each system."

          \consists "System_start_delimiter_engraver"
          systemStartDelimiter = #'SystemStartBrace
      }
  }

  \midi {
      \context {
          \type "Performer_group"
          \name "BraceStaff"
          \alias "ChoirStaff"
      }
  }

When compiling a file with these lines, LilyPond 2.10.33 does not complain 
about the definitions, but it DOES complain that it cannot find them:

  warning: can't find or create new `BraceStaff'

I'm attaching a sample LilyPond document to illustrate this problem.  Any 
help is appreciated, as this little problem has already taken rather a lot 
of hours of my time... :-)

Yours truly,

John Zaitseff

-- 
John Zaitseff                    ,--_|\    The ZAP Group
Phone:  +61 2 9643 7737         /      \   Sydney, Australia
E-mail: address@hidden   \_,--._*   http://www.zap.org.au/
                                      v

bracestaff.ly
Description: Text document