Min and Max System distances (Style | General | Page)

This is not a bug report yet. Some things are happening I do not understand and I would like to clarify them, before filing a bug report (if one is actually needed!).

I've been playing with the settings quoted in the subject and I have noticed a few things which surprised me. They are probably more or less strictly related, so they probably fit together.

1) Min and Max Distance values have no effect below 7

On any score with more than 1 system, try setting min and max system distance to anything less than 7 (set both to the same value, to avoid side effects): the system distance is stuck at 7.

Is it by design? (see below point 3)

2) If Max < Min, actual system distance can go below 7

(Granted, Max < Min does not make much sense) The actual system distance seems to be Max - Mix + 7, for instance:
Min: 7, Max: 0 => distance = 0
Min: 6, Max: 0 => distance = 1
and so on.

I doubt it is intended to work this way... However, this is currently the only way to obtain a system distance < 7 (but see point 3) again).

3) Music upper / lower margins affect EACH system

If the Music upper margin and Music lower margin are reduced, system distance is (or might be) reduced. For instance:
Min system dist: 0, Max system dist: 0, Upper margin: 2, Lower margin 2 => system distance = 2

I always understood the Upper and Lower margin as the margins of the whole page area occupied by the 'music'; i.e. how far down the page the first system begins (upper margin) and how far down the page the last system can go (lower margin).

It seems they are the upper and lower margin of each system. And, apparently, this interacts with (and in some cases nullifies) Min and Max system distance.

Is it by design?

Thanks,

M.