[JW Lua] FCCellMetrics:BottomPos/TopPos on staves with only one staff line

[Jan Angermüller]

Jari,

what's the content of FCCellMetrics.BottomPos/TopPos on
staves with just one line compared to staves with 5 lines ?

When comparing between "standard 5 line"-notation
and "1-line with full barline" I get the same TopPos,
but different BottomPos (the 1-line BottomPos seems
to be the middle line pos from the 5 line notation).

This is not what I would expect:
It's not quite clear to me, if TopPos/BottomPos refers to the
actual staff lines OR to the staff metrics itself including it's
top/bottom extensions with, for example, full barlines.
So:

In the first case, if TopPos/BottomPos were the actual positions of the 
staff lines
I would expect to get TopPos==BottomPos in a 1-line situation,
where TopPos[1 Line] == TopPos[5 Line] - (TopPos[5 Line] - BottomPos[5 
Line])*0.5  (i.e. the middle line)

In the second case, if TopPos/BottomPos were the max top/bottom position 
of the staff
(incl. barline heights), I would expect to have the same 
TopPos/BottomPos results
in a "1-Line full bar" and in a "5 line standard" as the barline height 
results
in the same overall height span.

So the current results seem strange to me.
What do you think ?

Have a nice day,
Jan