xfsettingsd: Add XfceGtkSettingsHelper - V2: GSettings/gtk-modules
Supersedes: !100 (closed)
Synchronization via gtk-modules requires patching GTK to work: see https://gitlab.gnome.org/GNOME/gtk/-/merge_requests/5733.
Fixes: libxfce4ui#38 (closed)
Related: !8 (merged), #179 (closed)
Edited by Gaël Bonithon