Hi Kenny (and all on the list): I have a simple defmd: (defmd gnc-point () (x (c-in 0)) (y (c-in 0)) (z (c-in 0)) (foreign-ptr (c_? (let ((ptr (or (^foreign-ptr) (fgn-alloc 'glInt 3 :gnc-point)))) (when ptr (setf (eltgli ptr 0) (^x)) (setf (eltgli ptr 1) (^y)) (setf (eltgli ptr 2) (^z))) ptr)))) This is a model for a point ( x | y | z ) and a foreign object pointer. The pointer shall be set to a an FFI memory pointer (via CFFI) when the instance is created. Also, the elements of the memory array (which is 3 glInt, this being three OpenGL Integers) shall be updated when any of the coordinates x y z is changed... I get x, y, and z updated but the foreign-ptr remains NIL ... What am I doing wrong ??? Thx! Frank