Thanks for your help. I checked in a changeset that makes Octave
compatible for unclosed contours
(http://hg.savannah.gnu.org/hgweb/octave/rev/096b1a159d1f). I noticed
again that for the same input Matlab has different visual output depending
on the host machine type (Linux, Mac). I went with the colors from the
Linux machine since that is what we already use for regular patch objects.