
Commit 16d371873
lifted the requirement for source actors to be
widgets, then got it wrong :rolling_eyes:
The content box is expected to be in actor coordinates, so the
allocation must be translated to (0, 0).
https://gitlab.gnome.org/GNOME/gnome-shell/-/issues/4593
Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/1969>