libwnck doesn't work well in gtk-perl?

[Shaya Potter <spotter cs columbia edu>]

I have this simple script that demonstrates my problem

#!/usr/bin/perl

use strict;
use Gtk2;
use Gnome2::Wnck;
Gtk2->init();

while (1) {
        sleep 1;

        my $screen = Gnome2::Wnck::Screen->get(0);
        $screen->force_update();

        my @windows_list = $screen->get_windows();

        foreach my $window (@windows_list) {
                my $name = $window->get_name();
                print "name = $name\n";
        }

}

I would expect it to print out all the window names on screen 0.  It 
does that the first time its called, but if window names are added or 
removed or changed, it just continues to print the original names.

I'm probably doing something stupid, but there isn't a lot of 
documentation for wnck in libtk-perl beyond the api (not even sure what 
force_update is for, just that the little documentation I saw, used it).

thanks.