strange keyboard problem

[Gilles Allard]

I'm replacing an old NCD Xterminal with a new thin client (HP T5745) 
powered with Debian V5.0.3
Versions are:
  xorg 1:7.3+20
  xserver-xorg-input-kbd 1:1.3.1-1
My legacy application, running on HPUX 10.20, has problems with the 
numLock.
Using xev, I've been able to determine that the new thin client handles 
the keyboard codes differently than the NCD terminal.
With NCD terminal:
  numLock only send one event when pressed and released
  numLock cause a change to state 0x40 (mod4?)
With the thin client:
  numLock sends 2 events (pressed and release)
  numLock cause a change to state 0x10 (mod2?)

I also notice that the CapsLock do not work with the ThinClient. The LED 
toggles but the caracter generated is always lowercase.

I'm not a X programmer and I'm confused by the complexity of keyboard 
configuration files (probably caused by the fact it is feature-rich). Would 
you please help me?

Questions:
- is it a bug?
- is it caused by a modification to Xwindow protocol?
- can I modify the xorg configuration to emulate the old way?

Thanks!