code: public void paintSliderThumbBackground(SynthContext context, Graphics g, int x, int y, int w, int h, int orientation) {
          if (context.getComponent().getClientProperty("Slider.paintThumbArrowShape") == Boolean.TRUE) {
  
              if (orientation == JSlider.HORIZONTAL) {
                  orientation = JSlider.VERTICAL;
              } else {
                  orientation = JSlider.HORIZONTAL;
              }
  
              paintBackground(context, g, x, y, w, h, orientation);
          } else {
              paintBackground(context, g, x, y, w, h, orientation);
          }
      }
docs: Paints the background of the thumb of a slider.
  
  @param context     SynthContext identifying the <code>JComponent</code>
  and <code>Region</code> to paint to
  @param g           <code>Graphics</code> to paint to
  @param x           X coordinate of the area to paint to
  @param y           Y coordinate of the area to paint to
  @param w           Width of the area to paint to
  @param h           Height of the area to paint to
  @param orientation One of <code>JSlider.HORIZONTAL</code> or <code>
  JSlider.VERTICAL</code>