The silly proble has drived me into mad.I installed SCIM.And I think all the configuration are right.Because all my softwares can display chinese correctly.And I can input the chinese characters when I working under rxvt and xterm.But under firefox,gaim and almost all the other softwares,when I press ctrl+space,SCIM's toolbar doesn't come out at all,so I can't use chinese input under these softwares' circumstance.What's the problem?
Bye the way:
type "locale" I get this:
LANG=zh_CN.gb18030
LC_CTYPE="zh_CN.gb18030"
LC_NUMERIC="zh_CN.gb18030"
LC_TIME="zh_CN.gb18030"
LC_COLLATE="zh_CN.gb18030"
LC_MONETARY="zh_CN.gb18030"
LC_MESSAGES="zh_CN.gb18030"
LC_PAPER="zh_CN.gb18030"
LC_NAME="zh_CN.gb18030"
LC_ADDRESS="zh_CN.gb18030"
LC_TELEPHONE="zh_CN.gb18030"
LC_MEASUREMENT="zh_CN.gb18030"
LC_IDENTIFICATION="zh_CN.gb18030"
LC_ALL=zh_CN.gb18030
and I wrote the followins into the file /etc/X11/xinit/xinitrc
LANG=zh_CN.gb18030
LC_ALL=zh_CN.gb18030
export XMODIFIERS=@im=SCIM
scim -d

When I launch FVWM,I will get these errors:
The font "-*-lucida-medium-r-normal--*-10-*-*-*-*-*-iso8859-1,*-r-*" does not support all the required character sets for the current locale zh_CN.gb18030
( Missing font charsets "GB2312.1980-0","ISO10646-1")

What may be the cause?THANKS!!!!!

I also find that I can use SCIM in softwares based on gtk,such as xmms,but not in softwares based on qt or gtk+,such as xffm,gftp,firefox,gaim.....

I have solved this probles by running the command "gtk-query-immodules-2.0 > /etc/gtk-2.0/gtk.immodules"!!!!!!Congratulations!!!!

hi vanbastern,

just out of curiosity: can you inform what linux distro you're using?