Mine

#!/usr/bin/perl
 
use Gtk2;
use Gnome2::Wnck;
use Data::Dumper;
 
Gtk2->init();
 
Gtk2->main_iteration while Gtk2->events_pending;
 
#my $screen = Gnome2::Wnck::Screen -> get_default();
my $screen = Gnome2::Wnck::Screen -> get(0);
$screen->force_update();
 
#neither of these gives the window list ordered by last active time
my @windowlist = $screen->get_windows_stacked();
my @windowlist = $screen->get_windows();