A checkbox "Material Boundaries" has been added to the Freestyle
options in the Layers tab of the Render buttons. By enabling the
option, any edge between two faces with different materials is
detected as a feature edge. In style modules, edges at material
boundaries can be tested with pyNatureUP1D(Nature.MATERIAL_BOUNDARY).
(http://freestyle.sourceforge.net/doc/html/index.html) has been
incorporated into the Blender/Freestyle Python API implementation
in the form of Sphinx-based embedded docstrings. Some C++-specific
descriptions of classes and functions were revised so that they are
suitable for Python programmers. Missing docstrings were filled,
and sparse descriptions were extended. By means of the new
documentation system for Blender, an up-to-date Freestyle Python
API reference will be part of the Blender 2.5 documentation.
