Part of the purpose of g_settings_get_child() was that it could be used
after you delay() a GSettings object, and then apply() all of the
settings together. In order for that to work, we need to share the
backend.
https://bugzilla.gnome.org/show_bug.cgi?id=720891
child_path = g_strconcat (settings->priv->path, child_name, NULL);
child = g_object_new (G_TYPE_SETTINGS,
+ "backend", settings->priv->backend,
"schema-id", child_schema,
"path", child_path,
NULL);