gtk/actionbar_since_3_12.go
func (a *ActionBar) SetCenterWidget(child IWidget) {
	if child == nil {
		C.gtk_action_bar_set_center_widget(a.native(), nil)
	} else {
		C.gtk_action_bar_set_center_widget(a.native(), child.toWidget())
	}
}
func (a *ActionBar) SetCenterWidget(child IWidget) {
	if child == nil {
		C.gtk_action_bar_set_center_widget(a.native(), nil)
	} else {
		C.gtk_action_bar_set_center_widget(a.native(), child.toWidget())
	}
}
//gtk_action_bar_set_center_widget(GtkActionBar *action_bar,GtkWidget *center_widget)