  /* Register our interest (in the form of a callback function) for
     any changes under the namespace that we just added.

     Parameters:
     - client: GConfClient object.
     - SERVICEPATH: namespace under which we can get notified for
                    changes.
     - gconf_notify_func: callback that will be called on changes.
     - NULL: user-data pointer (not used here).
     - NULL: function to call on user-data when notify is removed or
             GConfClient destroyed. NULL for none (since we don't
             have user-data anyway).
     - error: return location for an allocated GError.

     Returns:
     guint: an ID for this notification so that we could remove it
            later with gconf_client_notify_remove(). We're not going
            to use it so we don't store it anywhere. */
  gconf_client_notify_add(client, SERVICE_GCONF_ROOT,
                          keyChangeCallback, NULL, NULL, &error);
  if (error != NULL) {
    g_error(PROGNAME ": Failed to add register the callback: %s\n",
            error->message);
    /* Program terminates. */
  }

  g_print(PROGNAME ":main CB registered & starting main loop\n");
