private void createGUI() {
   panel.setBorder(BorderFactory.createTitledBorder("Terrain Content"));
   sizeSlider.addChangeListener(
       new ChangeListener() {
         public void stateChanged(ChangeEvent e) {
           setContentSize(sizeSlider.getValue() / 100.);
         }
       });
   offsetSlider.addChangeListener(
       new ChangeListener() {
         public void stateChanged(ChangeEvent e) {
           setVerticalOffset(offsetSlider.getValue() / 100.);
         }
       });
   panel.setLayout(new GridLayout(2, 1));
   sizeSlider.setMinimumSize(new Dimension(250, 35));
   sizeSlider.setBorder(
       BorderFactory.createTitledBorder(BorderFactory.createEmptyBorder(), "Size"));
   offsetSlider.setMinimumSize(new Dimension(250, 35));
   offsetSlider.setBorder(
       BorderFactory.createTitledBorder(BorderFactory.createEmptyBorder(), "Offset"));
   panel.add(sizeSlider);
   panel.add(offsetSlider);
 }