+/**
+ * Add the pair of role and surface to the client
+ *
+ * This function set the pair of role and surface to the client.
+ * This function is used for the client which has multi surfaces.
+ * If the model and relationship for role and surface(layer)
+ * is changed, this function will be changed
+ * Current Window Manager doesn't use this function.
+ *
+ * @param string[in] role
+ * @param unsigned[in] surface
+ * @return true
+ */