Re: Improves horizontal spacing of axis groups that SpanBar grobs traverse. (issue 4917046)

[mtsolo]

Hey all,

I just realized that in this patch, the Span_bar_stub_engraver could be
bumped down a level to the Lyric context to avoid the Grob_info
rerouting.  Lemme know if this seems like a good idea.

Another solution as well would be to create multiple SpanBars for the
same timestep in the same context (so that they never crossed places
where they're disallowed).  It'd get rid of a lot of the code, but it
wouldn't solve the problem of the inconsistent pure heights and it'd
make overrides for individual span bars a lot more difficult.
Furthermore, I'm not positive that cross-staff stems could have pure
heights that traverse multiple staves, and I'd like to use the same
logic (creating stubs in intermediary contexts between cross staff stems
to help with pure height approximations) for stems.

So, all that is to say that I'm trying to weigh the several options
available for this implementation and, as always, figure out the ones
that are most elegant while at the same time offering the most
re-usability for similar problems.

Cheers,
MS

http://codereview.appspot.com/4917046/