public function format_button($field)
    {
        $class = $this->columns[$field]['button_class'];

        $icon = $this->columns[$field]['icon'];
        if ($icon) {
            if ($icon[0] != '<') {
                $icon = '<span class="icon-'.$icon.'"></span>';
            }
            $icon .= '&nbsp;';
        }

        $this->current_row_html[$field] =
            '<button class="atk-button-small do-'.$field.'  '.$class.'" data-id="'.$this->model->id.'">'.
                $icon.$this->columns[$field]['descr'].
            '</button>';
    }