public function setSection(Section $section)
    {
        if ($section !== $this->_mainsection) {
            $this->_mainsection = null;
            $this->_level = $section->getLevel() + 1;
            if (0 === $this->_position) {
                $this->_position = 1;
            }
        }

        $this->_section = $section;

        return $this;
    }