Perl Gtk2::Window->list_toplevels

I'm using Perl Gtk2, and I want to see the list of open toplevel windows, using:

my @WL = Gtk2::Window->list_toplevels;
print STDOUT "TOP_WINDOWS:\n @WL\n";
TOP_WINDOWS: 
Gtk2::Window=HASH(0x23a4040) Gtk2::Window=HASH(0x23b5628) Gtk2::Window=HASH(0x1ca6238)

When I dump this list:
print STDOUT "DUMPER:\n", Dumper (@WL);
... it yields this:
DUMPER:
$VAR1 = bless( {}, 'Gtk2::Window' );
$VAR2 = bless( {}, 'Gtk2::Window' );
$VAR3 = bless( {}, 'Gtk2::Window' );

How do I process the above bless objects/value? I'm looking to get the name (or some kind of unique indicator) of each of the top_level window.

FOLLOW-UP QUSTION: The following doesn't work for "state" when I have additional widgets inside the toplevel - I got to believe I'm simply missing something here!

sub SM_callback ()
{
 my ($button, $data) = @_;

 my $DS       = $$data[0];
 my $hostname = $$data[1]; 

 state $DW;
 if ( ! $DW )
 { 
  $DW = Gtk2::Window->new('toplevel');
  $DW->set_default_size(400, 200);
  $DW->set_title($hostname);

  my $VB = Gtk2::VBox->new( 0, 0 );
  $DW->add($VB);

  my $TB = Gtk2::TextBuffer->new();
  $TB->set_text($hostname);

  my $TV = Gtk2::TextView->new_with_buffer($TB);

  my $SW = Gtk2::ScrolledWindow->new( undef, undef );
  $SW->add($TV);

  $VB->add($SW);

  $DW->show_all;
 }
 else
 {
  $DW->present;
 }

}

Here's my final solution:

By looping thru the list_toplevels in call_back funct, and if top_level window is already opened (or minimized) via checking get_name, then present it, otherwise create the new top_level window (and set_name for future checking).

#!/usr/bin/perl
# PURPOSE: Trying to determine how to recognize which toplevel window
#          is open to avoid opening same toplevel window muliple times.

use warnings;
use strict;
use feature qw(say state);
use Data::Dumper;
use Gtk2 -init;

#######################################################################
sub BN_callback 
{
 my ($button, $dataref) = @_;
 my $widget_name = $$dataref[0];

 my @open_TLW = Gtk2::Window->list_toplevels;

 foreach my $w ( @open_TLW )
 {
  my $open_name = $w->get_name;
  if ( $open_name eq $widget_name )
  {
   $w->present;
   return;
  } 
 }

 my $DW = Gtk2::Window->new('toplevel');
    $DW->set_default_size(400, 200);
    $DW->set_title($widget_name." sigtest_file");
    $DW->set_name($widget_name);
    $DW->show_all;
}
#######################################################################

my $TL = Gtk2::Window->new('toplevel');
   $TL->set_default_size(400, 200);
   $TL->set_position('center');
   $TL->set_name('Main_Window');
   $TL->signal_connect('delete-event' => sub { Gtk2->main_quit });
   $TL->show_all;

my $VB = Gtk2::VBox->new( 0, 0 );

$TL->add($VB);

my @BN = qw/BUTTON1 BUTTON2/;
foreach my $bn ( @BN )
{
 my $BT = Gtk2::Button->new($bn);
    $BT->set_name($bn); 
    $BT->signal_connect(clicked =>  \&BN_callback, [$bn]);

 $VB->add($BT);
}

$TL->show_all;
Gtk2->main;