Well, at least that explains what the New_fingering_engraver is!
As long as the engraver is under construction, is it easy to make the
skyline 'disappear' between dynamic marks so that it behaves more like
the figured bass engraver (see image)? Currently the entire row of
dynamic marks are shifted vertically to avoid a collision that can't
happen.
This isn't so much related to the engraver as it is to the way we
combine and calculate skylines. This is related to bug 584, and I hope
to fix it in the not-too-distant future.
Joe