public void addBall(int priority, int tryb) {
   Ball b = new Ball(plansza, canvas, tryb, Integer.parseInt(field.getText()));
   canvas.set(b);
   BallThread thread = new BallThread(b);
   thread.setPriority(priority);
   thread.start();
 }
        @Override
        public void mousePressed(MouseEvent arg0) {

          Random r = new Random();
          if (arg0.getButton() == 1) {
            if (arg0.getXOnScreen() + 30 < wymiar && arg0.getYOnScreen() < wymiar)
              plansza[arg0.getXOnScreen() - 30][arg0.getYOnScreen() - 60].color =
                  new Color(r.nextInt(255), r.nextInt(255), r.nextInt(255));
          } else {
            x = arg0.getXOnScreen() - 30;
            y = arg0.getYOnScreen() - 30;
          }
          canvas.repaint();
        }