the derived classes implements them differently, they still all conform to the
same interface.
-The items in a wxControlWithItems have (non empty) string labels and,
+The items in a wxControlWithItems have (non-empty) string labels and,
optionally, client data associated with them. Client data may be of two
different kinds: either simple untyped ({\tt void *}) pointers which are simply
stored by the control but not used in any way by it, or typed pointers