[Vala] how to avoid compile warnings with dbus

[con flatulence <conflatulence gmail com>]

Hello, I was playing with the dbus server example from the vala wiki* and
wanted to have a server with a constructor param, but when compiling there
is a warning (runs fine). Is there way to do this without compile warnings?

[DBus (name = "org.example.Demo")]
public class DemoServer : Object {
    private int counter;

    public int ping (string msg) {
        stdout.printf ("%s, counter=%d\n", msg, this.counter);
        return counter++;
    }

    public DemoServer(int initial_count) {
        this.counter = initial_count;
    }
}

[DBus (name = "org.example.DemoError")]
public errordomain DemoError { SOME_ERROR }

void main () {
    var initial_count = 3;

    Bus.own_name (BusType.SESSION, "org.example.Demo",
BusNameOwnerFlags.NONE,
        (conn) => {
            message("Bus acquired handler.");
            try {
                conn.register_object("/org/example/demo", new
DemoServer(initial_count));
            } catch (IOError e) {
                error(@"Could not register service: $(e.message)");
            }
        },
        () => { message("Name aquired handler."); },
        () => { error("Name lost handler."); }
    );

    new MainLoop ().run ();
}

[zach monica vala]$ valac --save-temps --pkg gio-2.0 dbus-server-arg.vala
/home/zach/misc/vala/dbus-server-arg.c: In function ‘_vala_main’:
/home/zach/misc/vala/dbus-server-arg.c:349:2: warning: passing argument 3
of ‘g_cclosure_new’ from incompatible pointer type [enabled by default]
/usr/include/glib-2.0/gobject/gclosure.h:195:11: note: expected
‘GClosureNotify’ but argument is of type ‘void (*)(struct Block1Data *)’

I'm using fedora 16, and vala from git commit 8fe20bf5500f

Looking at the C, I can see that block1_data_unref doesn't have the
GClosure* param of a GClosureNotify, adding a cast to GClosureNotify in the
C stops the warning, but I don't know if it's right. I'm not familiar with
GObject. How are the GClosure(s) created in the call to
g_bus_own_name_with_closures freed?

thanks
zach