- Upstream recommends spawn_async() instead of spawn_sync(), but the bindings
  for it are erroneous.

  See: https://gitlab.gnome.org/GNOME/vala/issues/721
       https://gitlab.gnome.org/GNOME/gobject-introspection/merge_requests/168
       https://gitlab.gnome.org/GNOME/vte/issues/227

- The upstream GTK devel branch has dropped some X11-specific APIs, including
  the interface for urgency hints. Eventually, this feature will have to be
  removed from weltschmerz too.

  See: https://gitlab.gnome.org/GNOME/gtk/merge_requests/766