@Nullable
  @Nls
  protected String validate(int index) {
    if (myRulesModel.getSize() < index) {
      return null;
    }

    final Object target = myRulesModel.getElementAt(index);
    if (target instanceof StdArrangementMatchRule) {
      for (int i = 0; i < index; i++) {
        final Object element = myRulesModel.getElementAt(i);
        if (element instanceof StdArrangementMatchRule && target.equals(element)) {
          return ApplicationBundle.message("arrangement.settings.validation.duplicate.matching.rule");
        }
      }
    }
    return null;
  }
@Nullable
  @Nls
  protected String validate(int index)