Turn out there is an solution.
First install scim-bridge
sudo apt-get install scim-bridge
then after installation, edit /etc/X11/xinit/xinput.d/scim as root
sudo gedit /etc/X11/xinit/xinput.d/scimFind the line on with GTK_IM_MODULE
change it into
GTK_IM_MODULE="scim-bridge"change the line with QT_IM_MODULE into
QT_IM_MODULE="scim-bridge"then restart your computer. or the ctrl-alt-backspace trick would work too.