/* offset/extent callbacks. */
void add_offset_callback (Grob *g, SCM proc, Axis a);
void chain_offset_callback (Grob *g, SCM proc, Axis a);
/* offset/extent callbacks. */
void add_offset_callback (Grob *g, SCM proc, Axis a);
void chain_offset_callback (Grob *g, SCM proc, Axis a);