static SCM ly_get_stencil_extent (SCM mol, SCM axis);
static SCM ly_set_stencil_extent_x (SCM,SCM,SCM);
static SCM ly_stencil_combined_at_edge (SCM,SCM,SCM,SCM,SCM);
static SCM ly_get_stencil_extent (SCM mol, SCM axis);
static SCM ly_set_stencil_extent_x (SCM,SCM,SCM);
static SCM ly_stencil_combined_at_edge (SCM,SCM,SCM,SCM,SCM);