public function getHeaderHtmlOptions()
    {
        $r = '';
        if ($this->htmlClass) {
            $this->headerHtmlOptions['class'] = (isset($this->headerHtmlOptions['class']) ? $this->headerHtmlOptions['class'] . ' ' : '') . $this->htmlClass;
        }
        foreach ($this->headerHtmlOptions as $k => $v)
            $r .= "$k = '$v' ";
        return $r;
    }