thanks for your answer, but I don't know, where the answer in your link is.
I searched in default.c, too and the num_lights (which is shown in the def_debug_pan is at this point in my level 4. So the yellow boxes around my 4 lights are okay, but I don't know, what the others are for. As mentioned above, there are no other lights.
is there some description about these yellow boxes, I missed?