public function setMainSection(Section $section)
    {
        if ($section === $this->_mainsection) {
            return $this;
        }

        $this->_mainsection = $section;
        $this->_position = 0;
        $this->_level = $section->getLevel();
        $section->setPage($this);

        return $this->setSection($section);
    }