Re: SystemStartBrace doesn't stretch vertically

[Jonathan Wilkes]

Here's the imlsp score I originally linked to when I brought up this
issue (compare system two to system three):

http://imslp.info/files/imglnks/usimg/d/dd/IMSLP00510-Debussy_-_Preludes__Book_2.pdf

Below is a better bug example.  The weight of the braces don't match. 
Stockhausen's "Gruppen" is a also great example of a mixture of many
different brace thicknesses/sizes.  The point is that I can't figure
out a way to change the thickness to customize the braces.  If you
uncomment staves 4 and 5 you'll see how distracting such a huge, thick 
brace would be in an orchestral setting (grouping the strings together, 
for example).

-Jonathan

Snippet:

\version "2.13.3"

\score {
    <<
      \new PianoStaff {
          <<
            \new Staff { c }
            \new Staff { c }
        >>
      }
        \new PianoStaff {
        <<
            \new Staff = "one" { c }
            \new Staff = "two" { c }
            \new Staff = "three" { c }
%            \new Staff = "four" { c }
%            \new Staff = "five" { c }
        >>
    }
  >>
}