Hi,
I don’t know how many may be aware, but, there is now an official 2.5 version of GrafX2 (tagged sources) by PulkoMandy and he asks that what is needed now is for everyone to update their port to the latest version and get the binaries uploaded to the download page. Perhaps some creative chaps can compile the latest for Mac OS, AmigaOS 3.x (68k, RTG), Aros,  Android, Raspberry Pi... etc?

source tarball for version2.5 is on the official download page...
http://pulkomandy.tk/projects/GrafX2/downloads

Also an active discussion on...
https://groups.google.com/forum/#!forum/grafx2

More info about GrafX2 can be found on...
http://grafx2.chez.com/

Hope someone out there is capable of this, because this program is absolute brilliance...