I know how:
 TkFont.configure('TkDefaultFont', 'family' => 'Lucida Sans Unicode', 'size' 
=> '10')

"Wang Dong" <wangdong2 / gmail.com> 写入消息新闻:eqoqm6$v4p$1 / news.cn99.com...
>I found TkOptionDB.add( "*font", "{Lucida Sans Unicode} 10" ) works∽ャbut 
>Tk::Tile didn't change.
>
>
> "Wang Dong" <wangdong2 / gmail.com> 写入消息新闻:eqopt7$umu$1 / news.cn99.com...
>> root = TkRoot.new do
>>    font {Tahoma 10 normal}
>> end
>>
>> can't work.
>>
>>
>
>