OK; when I fully installed GIMP2.10 (not portable), Mathmap works but buggy and some of the presets that use sliders look blank but the sliders are there. Still in need of a true GIMP2.10 compatible compile. Wish I was technical enough to do so, but, alas, I'm a novice at best when it comes to such things. Oh well; at least someone figured out how to keep GIMP 2.8x intact while installing 2.10x so I have access to both. :)