Calls the original class closure of a signal. This function should
only be called from an overridden class closure; see
g_signal_override_class_closure() and g_signal_override_class_handler().
Available since: 2.18
This function is not directly available to language bindings.
The instance the signal is being emitted on.
The data is owned by the caller of the function.
Parameters to be passed to the parent class closure, followed by a location for the return value. If the return type of the signal is
G_TYPE_NONE, the return value location can be omitted.