if (backBuffer == null) {
            throw new IllegalStateException("Buffers have not been created");
        }
        Win32GraphicsConfig gc =
            (Win32GraphicsConfig)getGraphicsConfiguration();
        gc.flip(this, (Component)target, backBuffer, x1, y1, x2, y2, flipAction);
    }
    @Override
    public synchronized Image getBackBuffer() {
        Image backBuffer = this.backBuffer;