JSplitPaneでディバイダの移動を連続的に再描画

JSplitPane leftPane = new JSplitPane(JSplitPane.VERTICAL_SPLIT);
JSplitPane rightPane = new JSplitPane(JSplitPane.VERTICAL_SPLIT);
JSplitPane centerPane = new JSplitPane(JSplitPane.HORIZONTAL_SPLIT);

leftPane.setTopComponent(new JScrollPane(new JTextArea("aaaaaaa")));
leftPane.setBottomComponent(new JScrollPane(new JTextArea("bbbb")));
rightPane.setTopComponent(new JScrollPane(new JTree()));
rightPane.setBottomComponent(new JScrollPane(new JTree()));
centerPane.setLeftComponent(leftPane);
centerPane.setRightComponent(rightPane);

leftPane.setResizeWeight(.5);
rightPane.setResizeWeight(.5);
centerPane.setResizeWeight(.5);

PropertyChangeListener pcl = new PropertyChangeListener() {
  @Override public void propertyChange(PropertyChangeEvent e) {
    if (JSplitPane.DIVIDER_LOCATION_PROPERTY.equals(e.getPropertyName())) {
      JSplitPane source = (JSplitPane) e.getSource();
      int location = ((Integer) e.getNewValue()).intValue();
      JSplitPane target = (source == leftPane) ? rightPane : leftPane;
      if (location != target.getDividerLocation())
          target.setDividerLocation(location);
    }
  }
};
leftPane.addPropertyChangeListener(pcl);
rightPane.addPropertyChangeListener(pcl);