Andre Klapper created an issue:
https://developer.gnome.org/gail-libgail-util/* is extremely outdated and should either be taken down or redirect to something. Probably to https://developer.gnome.org/gtk3/stable/GtkAccessible.html or maybe even already https://developer.gnome.org/gtk4/stable/GtkAccessible.html ? (Who knows what the future brings.)
Reason: https://help.gnome.org/misc/release-notes/3.2/ and https://developer.gnome.org/gtk3/stable/gtk-migrating-3-x-to-y.html state that "GNOME's Accessibility Implementation Library Gail has been completely merged into GTK+".
Sidenote: I'm also negatively impressed that https://developer.gnome.org/search?q=GAIL shows zero results.