uses the item name to name all windows that don't already have a name. will name windows indiscriminately, so query windows will also get named.

name_all_wins.pl

use Irssi;

sub name_all_windows {
    foreach my $window (Irssi::windows) {
        if ($window->{name} == "") {
            foreach my $item ($window->items) {
                $window->set_name($item->{name});
            }
        }
    }
}
sub list_all {
    foreach my $window (Irssi::windows) {
        my $name = $window->{name};
        Irssi::print("window name: $name");
    }
}
Irssi::command_bind('name_all_windows', 'name_all_windows');
Irssi::command_bind('list_all_window_names', 'list_all');