public function display()
    {
        if (!$this->visible || count($this->view->model) < 2) {
            return;
        }

        parent::display();

        $this->createEmbeddedWidgets();

        $columns = $this->view->getVisibleColumns();

        $tr_tag = new SwatHtmlTag('tr');
        $tr_tag->id = $this->id;
        $tr_tag->class = $this->getCSSClassString();
        $tr_tag->open();

        // find checkbox column position
        $position = 0;
        foreach ($columns as $column) {
            if ($column === $this->column) {
                break;
            } else {
                $position++;
            }
        }

        if ($position > 0) {
            $td_before_tag = new SwatHtmlTag('td');
            $td_before_tag->setContent('&nbsp;', 'text/xml');
            if ($position > 1) {
                $td_before_tag->colspan = $position;
            }

            $td_before_tag->display();
        }

        $td_tag = new SwatHtmlTag('td');
        if (count($columns) - $position > 1) {
            $td_tag->colspan = count($columns) - $position;
        }

        $td_tag->open();
        if ($this->title !== null) {
            $this->check_all->title = $this->title;
            $this->check_all->content_type = $this->content_type;
        }

        $this->check_all->extended_count = $this->extended_count;
        $this->check_all->visible_count = $this->visible_count;
        $this->check_all->unit = $this->unit;
        $this->check_all->tab_index = $this->tab_index;
        $this->check_all->display();

        $td_tag->close();

        $tr_tag->close();
    }