#define GUPPI_CURVE_IMPL0 (obj) #define GUPPI_IS_CURVE_IMPL0 (obj)
GtkObject +----GuppiDataImpl +----GuppiCurveImpl
#define GUPPI_CURVE_IMPL0(obj) ((obj) ? (GUPPI_CURVE_IMPL(obj)) : NULL)
#define GUPPI_IS_CURVE_IMPL0(obj) (((obj) == NULL) || (GUPPI_IS_CURVE_IMPL(obj)))