Description of problem:
For some reason I need to run the desktop under zh_CN.utf8 locale but Thunderbird under en_US.utf8.  When doing so, the mail text displayed in Thunderbird gets incorrect font rendering.  For all plain text mails, the Characters are displayed in a mixed fonts of WenQuanYi Zen Hei and AR PL UKai (see screenshot).  This affects all mail directories as well as the mail composition window, but the effect is limited to mail body text.  Subjects are not affected.

If Thunderbird is run under locale zh_CN.utf8, there's no inconsistency with mail body font.


Version-Release number of selected component (if applicable):
thunderbird-3.1.6-2.fc14.x86_64


How reproducible:
Always (under locale en_US.utf8)


Steps to Reproduce:
1.  Run Thunderbird with LC_ALL=en_US.utf8
2.  Read or compose plain text emails with Chinese characters

  
Actual results:
Chinese characters in message bodies are displayed in inconsistent fonts, greatly reducing readability. 


Expected results:
The fonts used should have been consistent.


Additional info:
This problem arises when the option "Use fixed width font for plain text messages" is selected.  This is my preferred setting, and the monospace font used is Nimbus Mono L.

I'm not sure whether this has anything to do with fontconfig.  I have not meddled with F14's default system-wide fontconfig settings.