Sorry for being too brief (and it seems that emailing a reply doesn’t work).
I was suggesting that you might be able to run ptxprint natively and ignore the whole parallels mess.
I really don’t know, I’ve not used any apple product since about 1998.
If google tells you than someone has worked out how to run glade / gtk-based applications written in python3 on your machine, and you can find a XeTeX distribution for your device, then there’s no need to go to parallels. It’s all cross-platform, open-source software, after all. I think it really depends on how hard Apple have made it to run GTK-based apps natively.
Failing that, maybe there’s a way you can run a linux virtual machine? PTXprint certainly runs on linux.