Glad to announce that #FontForge is officially migrating to GTK3 UI toolkit, starting with this PR: https://github.com/fontforge/fontforge/pull/5546
Special thanks to Joey Sabey https://github.com/Omnikron13 for his important proof-of-concept and GTK3 infrastructure work.
Special thanks to Fredrick Brennan @copypaste for his inspirational (really, no sarcasm) article at https://github.com/MFEK/docs/blob/master/doc/Why.md