81f62e9df8
Just as https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/352 did for the MetaBackgroundActor in mutter, let's fix the vignette shader in gnome-shell, too. Based on a patch originally propsed by Nikita Churaev, see https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/59. Fixes: https://gitlab.gnome.org/GNOME/gnome-shell/-/issues/3942 Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/2133>