xkb: Modifier key sends KeyRelease immediately

[xorg at henrik.synth.no]

Hi.

I am not able to map a specific key as a modifier key (AltGr).  Using 
xev, I can see that the key in question sends a KeyRelease immediately 
after KeyPress, even though I haven't released it yet.

This is a japanese laptop keyboard.  The key I am trying to map is two 
steps to the right from Space: 
http://www.notebookreview.com/picture.asp?f=27325

Other keys (such as the two keys adjacent to Space) does not send 
KeyRelease immediately, and works as intended.

Is there a way of turning off immediate KeyRelease for a specific key?

This is my xmodmap line for the key (I know, xmodmap is old school):

xmodmap -e "keycode 208 = ISO_Level3_Shift"

Best regards,
Henrik