PrintOperationPreview doesn't seem right

[Marko Anastasov <marko marko anastasov name>]

I'm having some difficulties with implementing a custom
preview dialog as a part of an example, one being related to
PrintOperationPreview interface. In short, PrintOperation
has this signal:

bool PrintOperation::on_preview(Gtk::PrintOperationPreview* preview,
                                ...)

and preview->gobj() is actually always null (preview itself is not).

Is it mis-wrapped somehow or what?

Marko