public function addSection($title, $callback = null, $icon = 'dropdown')
    {
        $section = $this->add(['AccordionSection', 'title' => $title, 'icon' => $icon]);

        // if there is callback action, then use VirtualPage
        if ($callback) {
            $section->virtualPage = $section->add(['VirtualPage', 'ui' => '']);
            $section->virtualPage->stickyGet('__atk-dyn-section', '1');
            $section->virtualPage->set($callback);
        }

        $this->sections[] = $section;

        return $section;
    }