There was a 3rd party toolkit called I believe Equal, then Lattitude for porting Mac Apps to Unix. Equal was used to port MS Word & Excel, and Lattitude for porting Adobe Photoshop and Illustrator.

It was essentially a reverse-engineered MacOS Rom Toolkit. It implemented most of System 7 as well as QuickDraw.

http://preserve.mactech.com/articles/mactech/Vol.13/13.06/Ju...