public function setSubCats($aCats)
    {
        $this->_aSubCats = $aCats;

        foreach ($aCats as $oCat) {
            // keeping ref. to parent
            $oCat->setParentCategory($this);

            if ($oCat->getIsVisible()) {
                $this->setHasVisibleSubCats(true);
            }
        }
    }