I tested this out on a mac and this does get rid of the GIL warning and everything works as expected.

Also as an FYI, I tested this with multiple windows trying to resize/zoom/pan between them and all of that state seemed good to me.

I also ran the threading example from here: #5675 (comment), updating data in background threads and that also played nicely with resizing/interactiveness and the free-threaded build. So I think we are at least OK with reasonable expectations for now. It will be good to get people hammering this a bit more and more exotic use-cases to be tested out.

edit: I also just added constrained_layout to test our interaction with kiwisolver's free threaded capability and that works nicely too.