public DetectCalibrationChessApp() {

    gray = new ImageFloat32(1, 1);

    JPanel panel = new JPanel();
    panel.setLayout(new BorderLayout());

    calibGUI = new GridCalibPanel(true);
    calibGUI.setListener(this);
    calibGUI.setMinimumSize(calibGUI.getPreferredSize());

    panel.add(gui, BorderLayout.CENTER);
    panel.add(calibGUI, BorderLayout.WEST);

    gui.addMouseListener(
        new MouseAdapter() {
          @Override
          public void mousePressed(MouseEvent e) {
            System.out.println("clicked at " + e.getX() + " " + e.getY());
          }
        });

    setMainGUI(panel);
  }