The #GtkBuilderConnectFunc to use when connecting signals in the class template
The data to pass to @connect_func
The #GDestroyNotify to free @connect_data, this will only be used at class finalization time, when no classes of type @widget_type are in use anymore.
3.10
For use in language bindings, this will override the default #GtkBuilderConnectFunc to be used when parsing GtkBuilder XML from this class’s template data.
Note that this must be called from a composite widget classes class initializer after calling gtk_widget_class_set_template().