75dafd8d9c
Add a screenshot-exclusive mode that makes the screencast button unreactive, and therefore disables screencasting. It doesn't change the visibility of the button though, as that's done by the codepath that checks if screencasting is supported. This will be used by the D-Bus callback to take interactive screenshots. Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/2999>