The link is broken now https://github.com/DutchmanDavid/DeluxePaint, but it seems to be available at https://github.com/historicalsource/DeluxePaint. I’m quite surprised to see it’s written in C, I would have thought that most of the apps back then were written in assembly.
Holy crap this is one of my favorite creative arts programs ever written!
I could just sit there for DAYS playing with the multicycle brush feature alone!
Unfortunately, restrictive license (probably) does not allow to make modifications to port it to modern systems. Although, probably it’s possible to do a legal port by creating secondary set of source files (written from scratch) that links with original code and offers interop with modern systems, offering user to download original source and to build it with new parts, as long as user is doing it “for personal use”.
You don’t need to do that.
All your DPaint-on-modern-platform wishes are already covered by GrafX2: https://gitlab.com/GrafX2/grafX2