public void showDifferences(DiffView diffView) {
    Frame window = WindowManager.getDefault().getMainWindow();

    if (dialog == null) {
      DialogDescriptor descriptor = dialogDescriptor(diffPanel);
      dialog = org.openide.DialogDisplayer.getDefault().createDialog(descriptor);
      dialog.setSize(640, 480);
    }
    diffPanel.setDiffView(diffView);
    dialog.setLocationRelativeTo(window);
    dialog.setVisible(true);
  }