Comment #1 on issue 2809 by [email protected]: A tutorial in the LM covering the *-*-spacing flexible vertical controls is required
http://code.google.com/p/lilypond/issues/detail?id=2809
It is probabably not the right time to discuss it, but in general I think instead of having an x-y-spacing matrix, usually just having before-x-spacing and after-x-spacing is sufficient, with every x-y-spacing being calculated as max (after-x-spacing, before-y-spacing). It might even be feasible to provide a #(setup-spacing-matrix) call that will do the appropriate calculation and set up a matrix (like we have now) from before/after settings.
