Ok Mike, I was trying to change this. It starts out with
Grob *vertical_alignment = Grob::get_root_vertical_alignment
if (!vertical_alignment) // we are at the beginning of a score, so no
need for stubs
axis_groups_ is a _map_. You take an _arbitrary_ element of the map
(whatever happens to have the first hash bucket), then call
get_root_vertical_alignment on it and work on the elements. And you never
clear out the map.
This is garbage. Total garbage. Please get a night of sleep and then
write down what this engraver is supposed to be doing. Not how, _what_.
It is part of a very large commit. If we can't figure out what this is for
and how it is related to the rest, the whole commit will need to get
reverted and rewritten, and there is likely quite a bit depending on it.