Now I feel old.
I remember I was in college and excited when I heard about GIMP. I had been running Linux for a year and wanted a photo editor but GIMP was written for the Motif GUI toolkit which was shipped with commercial Unix systems (Sun, HP, DEC, SGI, IBM) but on Linux it cost extra.
One of our campus sysadmins had the Linux Motif libraries and compiled GIMP and distributed static binaries to us.
There was an effort by "The Hungry Programmers" to develop LessTif as an open source Motif clone. You can see a reference to it in these old GIMP site from November 1995.
Motif 1.2 or above is required. (Ack! This restriction will be removed when LessTif becomes usable).
https://www.cc.gatech.edu/data_files/public/doc/gimp/index.h...
https://en.wikipedia.org/wiki/LessTif
The developers got frustrated with Motif and decided to write their own GUI X Window toolkit which became GTK (GIMP Tool Kit)
While I like and use GIMP quite often I think GTK has become more influential and important than GIMP.