function set_background_color($color)
    {
        $col = $this->munge_color($color);

        if (is_null($col)) {
            return;
            //$col = self::$_defaults["background_color"];
        }

        //see __set and __get, on all assignments clear cache, not needed on direct set through __set
        $this->_prop_cache["background_color"] = null;
        $this->_props["background_color"] = is_array($col) ? $col["hex"] : $col;
    }