Hi all,
I struggled a little bit with keyboard layouts in x2go. I found a way to enable numpad on a gnome 3.4.2 session (on debian Wheezy). I will try to make a traduction from my french version : go to system settings -> keyboard -> keyboard layout options -> Miscellaneous compatibility options -> numpad keys are always numerical (really not sure about this one).
Ask if you need to.
Cheers
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Nicolas FABRE