Here's a dumb Robofont idea that someone else might feel inclined to make better. I took the guts of Feature Preview and connected it to SpaceCenter. Oh, and I added support for feaPyFoFum. https://gi...
@nprofile1q... also have look at this using coretext to layout text with fea, https://github.com/typemytype/basicShapingRoboFontExtension