public void paintIcon(Component c, Graphics g, int x, int y) {
            Color color = c == null ? Color.GRAY : c.getBackground();             
            // In a compound sort, make each succesive triangle 20% 
            // smaller than the previous one. 
            int dx = (int)(size/2*Math.pow(0.8, priority));
            int dy = descending ? dx : -dx;
            // Align icon (roughly) with font baseline. 
            y = y + 5*size/6 + (descending ? -dy : 0);
            int shift = descending ? 1 : -1;
            g.translate(x, y);

            // Right diagonal. 
            g.setColor(color.darker());
            g.drawLine(dx / 2, dy, 0, 0);
            g.drawLine(dx / 2, dy + shift, 0, shift);
            
            // Left diagonal. 
            g.setColor(color.brighter());
            g.drawLine(dx / 2, dy, dx, 0);
            g.drawLine(dx / 2, dy + shift, dx, shift);
            
            // Horizontal line. 
            if (descending) {
                g.setColor(color.darker().darker());
            } else {
                g.setColor(color.brighter().brighter());
            }
            g.drawLine(dx, 0, 0, 0);

            g.setColor(color);
            g.translate(-x, -y);
        }