There is an inconsistency in the annotations due to the fact that constructors returning floating refs (like GtkWidgets) are marked as (transfer none) but constructors which return regular refs (like GObjects) are marked as (transfer full).

This causes an issue for the introspection information for g_object_newv() and possibly other similar functions. Here is the gir snippet for the return value of g_object_newv():

        <return-value transfer-ownership="full">
          <doc xml:whitespace="preserve">a new instance of</doc>
          <type name="Object"/>
        </return-value>

So basically, if I do gobject.new(Gtk.Button), g-i tells me I own the return value, but actually I don't! I could even end up with one less reference than expected and finalize the object one unref() call too early...

I think it would be more consistent to consider floating refs as proper references and asking the various g-i bindings to add that snippet of code after a function call:

if (constructor and transfer is full and g_object_is_floating(obj)) {
  g_object_ref_sink(obj);
}

Also this could fix the g_object_new() annotations as mentioned above.