Re: Issue 442 in lilypond: Enhancement: RemoveEmptyStaffContext shouldn't reduce PianoStaff to one staff

[lilypond]

Comment #7 on issue 442 by address@hidden: Enhancement:  
RemoveEmptyStaffContext shouldn't reduce PianoStaff to one staff
http://code.google.com/p/lilypond/issues/detail?id=442

I think that the default for a PianoStaff as opposed to a normal StaffGroup  
should be to
a) keep its systems alive together
b) keep its systems spaced together

While the "alive together" property arguably should be solved by letting  
RemoveEmptyStaffContext only work on top level Staffs/StaffGroups in the  
context having the respective engraver, making a spacing group would solve  
the problem of organ score spacing within an orchestral score, something  
currently done with more manual effort in the snippets.

Perhaps we need two different engravers?  One that determines an empty  
staff/staffgroup, and one that actually removes subordinate empty  
staff/group contexts if all of them have declared emptiness, passing  
emptiness upwards?

The keepalivewith property appears like a kludge that should, if at all, be  
maintained automatically.