Sets the marshaller of @closure. The marshal_data
of @marshal provides a way for a meta marshaller to provide additional
information to the marshaller. (See g_closure_set_meta_marshal().) For
GObject's C predefined marshallers (the g_cclosure_marshal_*()
functions), what it provides is a callback function to use instead of
@closure->callback.
Sets the marshaller of @closure. The marshal_data of @marshal provides a way for a meta marshaller to provide additional information to the marshaller. (See g_closure_set_meta_marshal().) For GObject's C predefined marshallers (the g_cclosure_marshal_*() functions), what it provides is a callback function to use instead of @closure->callback.