Add Khmer Keyboard to xfce Ubuntu

To install Khmer keyboard is not kinda hard but you can't find it via the UI. To add Khmer keyboard you have to follow below:

1. Go to start => Setting => Keyboard
2. Click Layout tab
3. uncheck "Use System deault"
4. click "Add" button
5. choose "Khmer (Cambodia)"
6. Click "OK"
7. open termianal and type command 

setxkbmap -option grp:switch,grp:alt_shift_toggle us,kh

Try to switch keyboard via "Alt+Shift" then you can type khmer.