g_dbus_proxy_new_for_bus_sync: assertion 'g_variant_is_object_path (object_path)' failed

[Germano Massullo]

Issue solved!

=== Problem n.1 ===
Line
gchar *object_path = "org/freedesktop/login1";
should be
gchar *object_path = "/org/freedesktop/login1";

=== Problem n.2 ===
Line
g_variant_get (ret, "(^ao)", &user_idle_time);
should be
user_idle_time = g_variant_get_uint64 (ret);