[Gtk-sharp-list] Glade example code

[Ian Pointer]

Hi, sorry about such a simple question, but I'm stumped. I'm a newcomer 
to C# (started messing around on Thursday). I've downloaded Mono and 
the gtk-sharp binding, and I've been playing around with the Glade 
facilities, using the guide posted at 
http://www.gotmono.com/docs/gnome/bindings/glade/glade.html for 
guidance. And I can get everything working fine, but there's a line 
that I don't understand:

[Glade.Widget] Button button1;

I get that this somehow connects the new GtkButton object to the one in 
the Glade file, but, uh, how does it do it? If you could just give me 
the name of the language feature being used so I could go and search 
for it, it would be a great help 8-).

Thanks a bunch in advance

__
Ian Pointer