@Override
  public ActionCallback select(final @NotNull Content content, final boolean requestFocus) {
    final TabInfo info = findTabInfoFor(content);
    if (info == null) return ActionCallback.DONE;
    final GridImpl grid = getGridFor(info);

    final ActionCallback result = new ActionCallback();
    tabs.select(info, false).doWhenDone(() -> grid.select(content, requestFocus).notifyWhenDone(result));

    return result;
  }
@Override
  public ActionCallback select(final @NotNull Content content, final boolean requestFocus)