TODO: include modification callback support here, perhaps
through intermediate Grob::instrumented_set_property( .. __LINE__ ).
*/
-#define set_property(x, y) internal_set_property (ly_symbol2scm (x), y)
+#define set_property(x, y) instrumented_set_property (ly_symbol2scm (x), y, __FILE__, __LINE__, __FUNCTION__)
#else
#define set_property(x, y) internal_set_property (ly_symbol2scm (x), y)
#endif