Gets vertical skylines from grob stencils

lily/page-layout-problem.cc

 /*
   This file is part of LilyPond, the GNU music typesetter.
 
   Copyright (C) 2009--2012 Joe Neeman <joeneeman@gmail.com>
 
   LilyPond is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.
 
@@ skipping 521 matching lines @@
 
 void
 Page_layout_problem::set_footer_height (Real height)
 {
   footer_height_ = height;
 }
 
 void
 Page_layout_problem::append_system (System *sys, Spring const &spring, Real indent, Real padding)
 {
-  Grob *align = sys->get_vertical_alignment ();
+  Grob *align = unsmob_grob (sys->get_object ("vertical-alignment"));
   if (!align)
     return;
 
   align->set_property ("positioning-done", SCM_BOOL_T);
 
   extract_grob_set (align, "elements", all_elts);
   vector<Grob *> elts = filter_dead_elements (all_elts);
   vector<Real> minimum_offsets = Align_interface::get_minimum_translations_without_min_dist (align, elts, Y_AXIS);
   vector<Real> minimum_offsets_with_min_dist = Align_interface::get_minimum_translations (align, elts, Y_AXIS);
 
@@ skipping 681 matching lines @@
     {
       if (Hara_kiri_group_spanner::has_interface (input[i]))
         Hara_kiri_group_spanner::consider_suicide (input[i]);
 
       if (input[i]->is_live ())
         output.push_back (input[i]);
     }
 
   return output;
 }