[Vala] Bug with Gtk3 and structs

[Andrew Higginson <at higginson gmail com>]

Hi, when I compile this code:
http://pastebin.com/EjdvB6RU

(Which generates this C code):
http://pastebin.com/ziQrEDQd

Instead of the code retrieving the struct I put into the GtkListStore,
and printing "The ID", it prints out gibberish like:
X�X

Why is this happening? Is it a problem with GTK3 or Vala?

Thanks

--
Andrew