/* Extract the fields of a position. */
#define POSN_WINDOW(posn) (XCAR (posn))
#define POSN_BUFFER_POSN(posn) (XCAR (XCDR (posn)))
/* Extract the fields of a position. */
#define POSN_WINDOW(posn) (XCAR (posn))
#define POSN_BUFFER_POSN(posn) (XCAR (XCDR (posn)))