sclass DesktopPaneWithSkyPicture extends JDesktopPane {
  BufferedImage image;
  
  *(BufferedImage *image) {}
  
  protected void paintComponent(Graphics g) {  
    paintSkyBackground(this, g, image);
  }
}

static JDesktopPane jDesktopPaneWithSkyPicture(S imageID, Color background) {
  ret setBackground(background, swingNu(DesktopPaneWithSkyPicture, loadImage2(imageID)));
}