protected function showCheckAll()
    {
        if (
            $this->getCheckboxCellRenderer() === null ||
            $this->getFirstAncestor('SwatForm') === null
        ) {
            $show = false;
        } elseif ($this->show_check_all === null && count($this->model) > 1) {
            $show = true;
        } elseif ($this->show_check_all === true) {
            $show = true;
        } else {
            $show = false;
        }

        return $show;
    }