@Nullable
  @Override
  public Object getData(@NotNull @NonNls String dataId) {
    if (DiffDataKeys.CURRENT_CHANGE_RANGE.is(dataId)) {
      int lineCount = getLineCount(getEditor().getDocument());
      return new LineRange(0, lineCount);
    }
    return super.getData(dataId);
  }
@Nullable
  @Override
  public Object getData(@NotNull @NonNls String dataId)