public void update(int score) 
    {
        // x and y relative to the image. baseline of leftmost character.
        int x = 5;      
        int y = 15;        
        // "Repaint" the score display         
        GreenfootImage image = getImage();
        // background color
        image.setColor(Color.DARK_GRAY);
        // "erase" the display
        image.fillRect(1, 1, WIDTH-2, HEIGHT-2);  
        // text color
        image.setColor(Color.WHITE);      

        // display image onto screen in place of the previous
        image.drawString("Score: " + score, x, y);  
        setImage(image);         
    }