I'm not sure why you say that. Bugzilla had a partial patch with some outstanding issues needing polish. Nobody rejected it, but nobody is working on it anymore. You're welcome to take https://github.com/Dudemanguy/gtk/pull/1 and continue the work in a gtk PR on gitlab.

You can jump in and implement it. The last few comments are basically "here's a patch that works", "ok, open a PR then" (and no follow up)