Comment #6 on issue 2990 by [email protected]: \RemoveEmptyStaves in StaffGroup context crashes
http://code.google.com/p/lilypond/issues/detail?id=2990
When you say "contexts containing", I'm assuming you mean "contexts creating." A VerticalAxisGroup represents a line of music on the page. Think of it like a PaperColumn rotated 90 degrees. As such, the only contexts that ever create them should be ones that govern the creation of a line of music on the page (Staff, Dynamics, Lyrics, DrumStaff, TabStaff, etc.). Including an Axis_group_engraver means that you want to create a one and only one VerticalAxisGroup in a context and no VerticalAxisGroup in inferior or superior contexts on the tree.
