This article was first written in May 2004 for the BeezNest technical website (http://glasnost.beeznest.org/articles/126)
GNOME seems to have its own way of managing the numeric keypad, which leads to something very frustrating: the dot (or comma) on the keypad is understood as dot, while the decimal separator in Belgium should be the comma.
To change that, I have not found a better solution that to add a line like this in /etc/X11/Xmodmap create it if needed:
keycode 91 = KP_Delete comma
This has been tested on Debian Woody and Debian Sarge, both using GDM and a GNOME Desktop.