@Override
  public boolean isEnabled(ViewContext context, Content[] selectedContents, String place) {
    int count = 0;
    for (Content c : context.getContentManager().getContents()) {
      if (c.isCloseable() && ++count > 1) return true;
    }
    return false;
  }
@Override
  public boolean isEnabled(ViewContext context, Content[] selectedContents, String place)