Revert "ui: Remove maybe_redirect_mouse_event"

This reverts commit 6c7a51378fcfcbf9b5332f9f867cb006109a45f6.

It seems we still have issues with GDK's grab tracking getting confused.
That's unfortunate.
Revert "Update to latest xdg-shell protocol"

This reverts commit fd5c14550a0e75912beeff9d203dbcaef90f0368.

Again, pushed by accident, whoops.