Yea, that one made me smile as I thought that might work but I don't have enough guts to give it a try. I am not sure what the material is in that sensor port. I am suspecting it is a fiber optic material taking the available light down to the circuitry but it would be my luck that the felt tip or dab of paint would ruin it. But it probably would work just fine and what I should try if I had the nerve.
Thanks