Re: SystemStart changes after stop/startStaff - how to get it back

[Aaron Hill]

On 2020-04-12 3:50 am, Thomas Morley wrote:
> Hi,
>
> consider the following code:
>
>
> mus = \new Staff { R1 \break R \stopStaff s \startStaff R \break R 
> \break R }
>
> \new StaffGroup
>   \with {
>       systemStartDelimiterHierarchy =
>         #'(SystemStartBracket (SystemStartBrace a b c))
>   }
>   << \mus \mus \mus >>
>
>
> The SystemStartBrace vanishes after stop/startStaff.
> I'm at a loss here, it does not work out of the box for every version
> from 2.12.3 up to master.
>
> Any chance to get the additional SystemStartBrace back?

Yes, but it might have side-effects:

%%%%
systemStartDelimiterHierarchy =
  #'(SystemStartBracket
      (SystemStartBrace a b c)
      (SystemStartBrace a b c))
%%%%

Since \stopStaff and \startStaff create new StaffSymbols, it appears the 
System_start_delimiter_engraver thinks that these are extra staves in 
parallel, so your hierarchy says to do this:

   ( / =====
   < | =====
   ( | =====
     | =====
     | =====
     \ =====

Of course, the StaffSymbols never appear at the same time, because they 
are meant to be replacements.  But the SystemStartBrace only spans the 
first three staves, so it does not apply in the latter part of the 
score.

Knowing that a duplicate set of staves will appear at some point, you 
can lie about the hierarchy as my hack above does.  This allows the 
second set of StaffSymbols to be grouped as desired.

Ultimately, System_start_delimiter_engraver needs to be watching for 
\stopStaff and \startStaff events so it can clean up and rebuild its 
StaffSymbol collection rather than just append to the existing one.


-- Aaron Hill