I have compiled The Dark Mod on Gentoo Linux (I detailed my experience in another post).
I have a problem: the light gem is always completely dark. Guards will react to noise and to touch, but I could stand in front of them making faces and they will politely ignore my presence.
I have bisected the commits and tracked back the problem to commit #4379.
Reverting that single commit fixes my problem. Not surprisingly, I do not understand that commit. I can try things though.
I should assume this does not happen on Windows. Is this material for a bug report?