While the events when processing keybindings are quite obviously
key events, the individual structs are all opaque and all public
API is provided by the generic ClutterEvent type. That means that
any handler that uses the passed in event must cast it to
ClutterEvent anyway, so drop the cast to ClutterKeyEvent when
processing key events.
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/4080>
When a key binding is removed, and a trigger key sequence is dispatched
before the idle callback that resolves and updates the actual binding,
we should handle that gracefully.
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/3711>