gtk/gtk.go
func (v *RadioButton) JoinGroup(groupSource *RadioButton) {
	var cgroup *C.GtkRadioButton
	if groupSource != nil {
		cgroup = groupSource.native()
	}
	C.gtk_radio_button_join_group(v.native(), cgroup)
}
func (v *RadioButton) JoinGroup(groupSource *RadioButton) {
	var cgroup *C.GtkRadioButton
	if groupSource != nil {
		cgroup = groupSource.native()
	}
	C.gtk_radio_button_join_group(v.native(), cgroup)
}
// JoinGroup is a wrapper around gtk_radio_button_join_group().