Sets a dummy callback for
source. The callback will do nothing, and
if the source expects a #gboolean return value, it will return
(If the source expects any other type of return value, it will return
NULL value; whatever
g_value_init() initializes a
GValue to for
If the source is not one of the standard GLib types, the
closure_marshal fields of the
structure must have been filled in with pointers to appropriate functions.
The data is owned by the caller of the function.