+ DECLARE_SCHEME_CALLBACK (simple_vertical_skylines_from_stencil, (SCM smob));
+ DECLARE_SCHEME_CALLBACK (vertical_skylines_from_stencil, (SCM smob));
+ DECLARE_SCHEME_CALLBACK (vertical_skylines_from_element_stencils, (SCM smob));
+ DECLARE_SCHEME_CALLBACK (simple_horizontal_skylines_from_stencil, (SCM smob));
+ DECLARE_SCHEME_CALLBACK (horizontal_skylines_from_stencil, (SCM smob));
+ DECLARE_SCHEME_CALLBACK (horizontal_skylines_from_element_stencils, (SCM smob));