Comment 10 for bug 1500912

seems it has something to do with the keyboard input method system which is in unity by default at "ibus"

there is a way to set it to "none" which might have the same effect as to set it via environment variable:
http://askubuntu.com/questions/472562/how-to-change-keyboard-input-method-system-to-none-in-ubuntu-gnome

however, I need to find out more about input method, what it is all about and why it behave strange in synapse,...