Font Mapping in Messenger

As native unicode IM program, Live Messenger is able to display any
characters if installed proper fonts.
But it seems a bit strange to display East Asian characters on East Asian
version Windows XP or Vista, it mixed up the typeface in the same message in
the input box and the display box.

For example, here is the Nick name using Traditional Chinese and Japanese.
綾風�希[ティッシュ姫]
The first 5 characters, including the left square bracket, displayed in 10px
PMingliu, but, after the first Japanese character, other characters displayed
in 11px MS PGothic!

Another one, the sentence,
今日è¦�è�½åŸ‹ 焔～ホãƒ*ラ アルトãƒ�リコ2ヒュãƒ*ノスコンサート サイド ç´…å…ˆ
The first five characters(今日��埋) in Traditional Chinese (also in CP950)
displayed in MS PGothic! Only the last 2 characters(ç´…å…ˆ) displayed in 10px
PMingliu.

More strange one,
ã�Ÿã�*ä¿¡ã�˜ã�§â˜†é*‚コーラ 說:
The whole is not displayed in PMingliu, but in MS PGothic (ã�Ÿã�*ä¿¡ã�˜ã�§â˜†é*‚コーラ
,Japanese) and Gulim (說 ,Traditional Chinese).

And if I use Traditional Chinese and Simplified Chinese (even some Hong Kong
characters for spoken) in the same message,
�簡轉��简转�
It only displayed in 11px SimSun.

I have set the message font in PMingliu (Vista one is able to display the
Traditional and Simplified Chinese, Japanese, as this font have fully covered
CJK Unified Ideographs and Extension A characters) or Tamaha (is able to
display any characters because of Fonk Linking), but it still fixed to use
other fonts to display the messages.

I have searched about this problem, it seems that Live Messenger used the
Rich Edit 2.0, however I have no idea about it...
So, how to make the message in the same font without deleting other font?