code: func (v *Application) GetWindowByID(id uint) *Window {
  	c := C.gtk_application_get_window_by_id(v.native(), C.guint(id))
  	if c == nil {
  		return nil
  	}
  	return wrapWindow(glib.Take(unsafe.Pointer(c)))
  }
docs: // GetWindowByID is a wrapper around gtk_application_get_window_by_id().