Consider this snippet.
```
\book {
#(set-global-staff-size 20)
{ c' }
}
\book {
#(set-global-staff-size 10)
{ c' }
}
```
Section 'Setting the staff size' in the NR says
To set the staff size globally for all scores in a file (or in a
\book block, to be precise), use set-global-staff-size [...]
This implies that `set-global-staff-size` is restricted to `\book` if
used within.
However, the above example fails: In both created PDF files, the staff
size is 20pt, which means that the second call to
`set-global-staff-size` does nothing.
What is wrong? The documentation or LilyPond's behaviour?
Werner
