code: func WindowNew(t WindowType) (*Window, error) {
  	c := C.gtk_window_new(C.GtkWindowType(t))
  	if c == nil {
  		return nil, nilPtrErr
  	}
  	return wrapWindow(glib.Take(unsafe.Pointer(c))), nil
  }
docs: // WindowNew is a wrapper around gtk_window_new().