http://forum.ubuntu.org.cn/viewtopic.php?t=343717
/etc/X11/xinit/xinput.d/default file:
#
# This configuration provides default IM setting (user edittable)
# See im-switch(8) and /usr/share/doc/im-switch/README.Debian .
#
# Define IM for traditional X application with XIM
#
# XIM server name used for XMODIFIERS="@im=$XIM"
# XIM program /path/filename
# XIM program command line arguments
#
# These were traditional setting before uim and scim for CJK languages
# Language LC_CTYPE XIM server XMODIFIERS Start key
# Japanese ja_JP* kinput2 "@im=kinput2" Shift-Space
# Korean ko_KR* ami "@im=Ami" Shift-Space
# Chinese(T) zh_TW.Big5 xcin "@im=xcin-zh_TW.big5" Ctrl-Space
# Chinese(S) zh_CN.GB2312 xcin "@im=xcin-zh_CN.GB2312" Ctrl-Space
#
XIM=ibus
XIM_PROGRAM=/usr/bin/ibus-daemon
XIM_ARGS="--xim"
XIM_PROGRAM_XTRA=
# Set following variable to non-zero string if program set itself as deamon
XIM_PROGRAM_SETS_ITSELF_AS_DAEMON=
#
# Define GTK and QT IM module
# They may or may not be using xim as the IM.
#
GTK_IM_MODULE=ibus
QT_IM_MODULE=ibus
#
# Define lists of packages neded for above IM to function
#
DEPENDS="ibus, ibus-gtk, ibus-qt4"
#
# Define X start up hook script to update IM environment
#