public function addColumn($width = 'auto')
    {
        /** @type View $c */
        $c = $this->add('View');
        if (is_numeric($width)) {
            $this->mode = 'grid';
            $c->addClass('atk-col-'.$width);

            return $c;
        } elseif (substr($width, -1) == '%') {
            $this->mode = 'pct';
            $c->addStyle('width', $width);
        }
        $this->template->trySet('row_class', 'atk-cells');
        $c->addClass('atk-cell');

        return $c;
    }