For those interested, it is clearer to me what happens with Win 8.1 and older programs on a high-res screen (3200x1800 on 15 inches). It seems that there is straight pixel doubling. Whether there is super-sampling (as occurs with the Macbook Retina Pro but, not yet, with the Mac Pro and 4K monitors), I don't know. The attached screenshot shows Eudora's rendering of Arial next to MSW's. Eudora is not at all fuzzy (as many older programs are on a Macbook Retina) but it does not have high resolution either. This seems to me an acceptable and amazingly competently realized compromise. Microsoft of course hasn't received a particle of credit for this.