Update Information part 2 

my $screen = Gnome2::Wnck::Screen->get_default();
our $old_window_xid   = undef;
our $old_window_title = undef;
sub window_changed {
    my $screen = shift;
    my $active_window = $screen->get_active_window();
    if (defined $active_window) {
        my $active_window_xid = $active_window->get_xid();
        if ($active_window_xid ne $old_window_xid) {
            if (defined $old_window_xid) {
                set_title($old_window_xid, $old_window_title);
            }
            $old_window_xid   = $active_window_xid;
            $old_window_title = $active_window->get_icon_name();
            set_title($active_window_xid, 
	              title_format($active_window));
        }
    }
}
$screen->signal_connect(active_window_changed => \&window_changed);