gtk4: Deadlock during shutdown from GstPlay

added Blocker label

mentioned in merge request !1024 (merged)

Maybe we can do it asynchronously instead of waiting for the flushing to finish, and make that work correctly by passing a reference to the context/display into the closure running on the main thread.

This doesn't affect the 0.9 branch, right? Only main?

It also affects the 0.9 branch, but we don't yet build the plugin as part of cerbero. I was going to fix this after discussing some details with @ystreet.