function getFontDescender($size)
    {
        // note that this will most likely return a negative value
        if (!$this->numFonts) {
            $this->selectFont($this->defaultFont);
        }

        //$h = $this->fonts[$this->currentFont]['FontBBox'][1];
        $h = $this->fonts[$this->currentFont]['Descender'];

        return $size * $h / 1000;
    }