[xmonad] Bug with ghc's XFT binding?

[Chengqi(Lars) Song]

hi,

I'm using xmobar with xmonad. I found that it's hard to display Chinese characters in xmobar. So I made the following tests:

Set up:
 1. my system locale is en_US.utf-8
 2. my xmobar is compiled with xft and utf8 support
 3. in my xmobarrc, the font is set to be "xft:monospace-6"
 3. in terminal, I run "cat | xmobar ~/.xmobarrc"

The results:
 1. English can be displayed well. But all Chinese characters are displayed in squares.
 2. If I change the font in xmobarrc to be a Chinese font "xft:SimSun-6", then the display is correct.
 
So I guess it might be a bug of xft binding in ghc's library. Do you have similiar experience in xmobar or someother programs?

Regards
Lars