Please describe the problem:
Updated to vala 0.5.7. 

Subclasses of GtkWidget and GtkContainer can nolonger access these(not limited within) member functions, if they are overriden in the subclass.

gtk_widget_size_allocate
gtk_widget_size_request
gtk_widget_realize
gtk_widget map
gtk_widget_expose_event

gtk_container_add
gtk_container_remove

The common characteristics of these member functions are that they have a signal and a corresponding emitter. 

The signal is decleared as public virtual. The emitter is not declared.




Steps to reproduce:
using Gtk;

    public class MenuLabel: Gtk.Container {
        private Label _label_widget = new Label("");
        private Label _accel_widget = new Label("");
        public MenuLabel() {
            _accel_widget.visible = false;
            _label_widget.visible = false;
            _label_widget.use_underline = true;
            _label_widget.ellipsize = Pango.EllipsizeMode.END;
            this.add(_label_widget);
            this.add(_accel_widget);
        }
        public override void add(Widget child) {
            if(!(child is Label)) {
                warning("only GtkLabel is accepted");
                return;
            }
        }
    }
}


Actual results:
[rainwoodman@localhost libgnomenu]$ valac -C /tmp/t.vala --pkg gtk+-2.0
t.vala:11.4-11.11: error: Access to private member `Gtk.Container.add' denied
			this.add(_label_widget);
			^^^^^^^^
t.vala:12.4-12.11: error: Access to private member `Gtk.Container.add' denied
			this.add(_accel_widget);
			^^^^^^^^
Compilation failed: 2 error(s), 0 warning(s)


Expected results:


Does this happen every time?
Yes

Other information:
I am filing this as a blocker because this is rendering Vala 0.5.7 unusable for writing any real widgets since overriding these functions is a must for implementing any useful widgets.