function enable_highlighting($flag = true)
    {
        $flag = $flag ? true : false;
        foreach ($this->lexic_permissions as $key => $value) {
            if (is_array($value)) {
                foreach ($value as $k => $v) {
                    $this->lexic_permissions[$key][$k] = $flag;
                }
            }
            else {
                $this->lexic_permissions[$key] = $flag;
            }
        }
    }