x11: fails to advertise _GTK_EDGE_CONSTRAINTS support
I was recently trapped in an X11 session with gnome-shell 3.30.2, and noticed that my windows lost their corner resize cursors. Some debugging revealed that GTK+ is looking for _GTK_EDGE_CONSTRAINTS in _NET_SUPPORTED. But its not there, despite _GTK_EDGE_CONSTRAINTS being set on toplevels.