Thanks for your help. I solve the problem with your instruction.
Yukihiro Nakadaira wrote:
> Zhong, Dingkun wrote:
>> I try to map the alt key to some function in gvim, but it does not
>> work. I use the zh_CN.UTF-8 locale in linux with gnome, and gvim is
>> gtk version. After mapping <M-x> (x is a letter or number key) in
>> insert mode, I get an x in insert mode when type the <M-x> key. But
>> mapping <M-Left> (and <M-Right>...) do work.
>> I change the LC_CTYPE to en_US.UTF-8, the mappings have no problem.
>> But I can not input Chinese if I set LC_CTYPE to en_US.UTF-8. Is
>> there a solution to this problem? Thank you.
> I guess your 'imactivatekey' is not set. In that case, Vim always pass
> inputted key to Input Method. If the Input Method catch the <M-x> key
> drop the modifier, "x" is inserted. It happened for me when
> GTK_IM_MODULE=xim. I can use <M-x> when 'imactivatekey' is set to
> or GTK_IM_MODULE=scim (or uim or iiim).