I don't think its going to help much Stu. Aren't most laptop screens backlighted anyway. Your still going to get white light through even with a colour scheme. (or so i've been reliably informed). Red Gel with a cardboard boarder and stick on velcro.
Has worked reliably for 4 years on one lappy and 3 on the other. I suppose one day i'll make a new one but so far haven't needed to.