I've installed CentOS 6.5 - 32-bit and am using GNOME, connecting to a Citrix App server. While connecting, I'm not able to use the Numlock in the session. So from a blog I've found how to fix this usijg the following command:
xmodmap -e 'remove mod2 = Num_Lock'
After executing this command, Numlock works fine within the Citrix session, but the Numlock LED is no longer lighting up (on/off) when pressed.
When the session is closed, the Numlock continues to not work in other Linux apps until the above command is executed from a terminal.