It’s really rare for a project to completely rewrite to a new toolkit. VLC in circa 2007 did it (moved to Qt - even stole their volume control widget directly from Amarok at the time). GCompris ended up as a KDE project despite originating in Gnome (along with toolkit change, but it weirdly kept the name). LXDE->LXQT also. But I don’t actually have that many examples.
LKML and patch: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=0fc810ae3ae110f9e2fcccce80fc8c8d62f97907
He cites his work as being a variant of a patch submitted by another developer, Josh Poimboeuf. It’s a team effort folks :)