code: private void paintButton(Graphics2D g, JComponent c, int width, int height) {
          g.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
  
          Shape s = createButtonPath(CornerSize.BORDER, 0, 2, width - 2, height - 4);
  
          g.setPaint(getComboBoxButtonBorderPaint(s, type));
          g.fill(s);
  
          s = createButtonPath(CornerSize.INTERIOR, 1, 3, width - 4, height - 6);
          g.setPaint(getComboBoxButtonInteriorPaint(s, type));
          g.fill(s);
      }
docs: Paint the button shape.
  
  @param g      the Graphics2D context to paint with.
  @param c      the component to paint.
  @param width  the width.
  @param height the height.