public function load_config_file($file)
    {
        if (!is_readable($file)) {
            return;
        }

        include $file;

        // read comments from config file
        if (function_exists('token_get_all')) {
            $tokens    = token_get_all(file_get_contents($file));
            $in_config = false;
            $buffer    = '';

            for ($i = 0; $i < count($tokens); $i++) {
                $token = $tokens[$i];
                if ($token[0] == T_VARIABLE && ($token[1] == '$config' || $token[1] == '$rcmail_config')) {
                    $in_config = true;
                    if ($buffer && $tokens[$i+1] == '[' && $tokens[$i+2][0] == T_CONSTANT_ENCAPSED_STRING) {
                        $propname = trim($tokens[$i+2][1], "'\"");
                        $this->comments[$propname] = $buffer;
                        $buffer = '';
                        $i += 3;
                    }
                }
                else if ($in_config && $token[0] == T_COMMENT) {
                    $buffer .= strtr($token[1], array('\n' => "\n"));
                }
            }
        }

        // deprecated name of config variable
        if (is_array($rcmail_config)) {
            return $rcmail_config;
        }

        return $config;
    }