Consider this extreme example for demonstration purposes.
```
#(set-global-staff-size 5)
{
f'1 | f'1 \bar "|."
}
```
As can be seen in the attached image, the bar lines – especially for
the end bar – are too thick. While it is correct to not adjust the
bar lines for `\magnifyStaff` so that they harmonize with staves in
other sizes in the same system, this doesn't seem right for
`set-global-staff-size`, which influences everything.
It's also correct to have a 'fatter' look for staff lines and glyphs
at smaller sizes since it increases readability – have a look at old,
manually engraved pocket scores of Eulenburg, for example. But in the
given example the bar lines are *far* too fat.
I know that the thickness of bar lines can be manually adjusted.
However, I wonder why we have this ugly appearance as the default
setting.
BTW, I couldn't find something related to this problem either in the
bug tracker or in the mailing lists. Shall I open an issue?
For me, the correct behaviour would be to increase thickness of bar
lines in sync with the optical size of the Emmentaler font: in the
range Emmentaler-11 to Emmentaler-26, derive the bar line thickness
from the intended staff line thickness. Below and above this range,
scale linearly. Actually, I think this should be done for staff
lines, too...
Werner
