Example: Fixed

public class Application : Gtk.Window {

public Application () {
// Prepare Gtk.Window:
this.title = "My Gtk.Fixed";
this.window_position = Gtk.WindowPosition.CENTER;
this.destroy.connect (Gtk.main_quit);
this.set_default_size (350, 70);

// The Fixed:
Gtk.Fixed fixed = new Gtk.Fixed ();
this.add (fixed);

Gtk.Button button1 = new Gtk.Button.with_label ("Foo");
fixed.put (button1, 0, 0);

Gtk.Button button2 = new Gtk.Button.with_label ("Bar");
fixed.put (button2, 50, 50);
}

public static int main (string[] args) {
Gtk.init (ref args);

Application app = new Application ();
app.show_all ();
Gtk.main ();
return 0;
}
}

 valac --pkg gtk+-3.0 Gtk.Fixed.vala

See: