Re: Issue 1031 in lilypond: constantly-changing input/regression/rest-collision-beam-note.ly

[lilypond]

Comment #7 on issue 1031 by pnorcks: constantly-changing  
input/regression/rest-collision-beam-note.ly
http://code.google.com/p/lilypond/issues/detail?id=1031

Thank you for the helpful suggestions, Han-Wen.

Your intuition is correct: the problem is with the sorting vectors of  
pointers to
objects.

For the case with rest-collision-beam-note.ly, the specific sort that is  
problematic
is in Axis_group_interface::skyline_spacing() on axis-group-interface.cc:637

  vector_sort (elements, staff_priority_less);

For a solution, are you suggesting that we add a new member to the Grob  
class that
records a unique Grob ID?  I'm not I understand correctly what you refer to.