scrollbar.setOpaque(true);
  protected void installDefaults()  {    UIDefaults defaults = UIManager.getLookAndFeelDefaults();    scrollbar.setForeground(defaults.getColor("ScrollBar.foreground"));    scrollbar.setBackground(defaults.getColor("ScrollBar.background"));    scrollbar.setBorder(defaults.getBorder("ScrollBar.border"));    maximumThumbSize = defaults.getDimension("ScrollBar.maximumThumbSize");    minimumThumbSize = defaults.getDimension("ScrollBar.minimumThumbSize");  }