a91fd4a72c
This allows us to destroy and create a new offscreen dynamically, when the rotation or color state changes. An idle gsource with priority higher than CLUTTER_PRIORITY_REDRAW is used to ensure the an offscreen exists when required without having to allocate in the redraw process. Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/3930>