@Override
 public void dispose() {
   IBundleModel model = getBundleModel();
   if (model != null) model.removeModelChangedListener(this);
   super.dispose();
 }
 /* (non-Javadoc)
  * @see org.eclipse.ui.forms.AbstractFormPart#dispose()
  */
 public void dispose() {
   IProductModel model = getModel();
   if (model != null) model.removeModelChangedListener(this);
   super.dispose();
 }