EXAMPLE

/* The given hook will be called after every change */
/* in the string gadget. It receives a pointer to   */
/* a pointer to the current contents in register a1 */
/* (see MUIM_CallHook for details)                  */

DoMethod(str,MUIM_Notify,
   MUIA_String_Contents, MUIV_EveryTime,
   str, 3, MUIM_CallHook, &hook, MUIV_TriggerValue);