I was interested to see how much I needed to change the supplied code to get something running with Tk

use strict;
use warnings;
use Tk;

my @cursors = qw/ 12 24 48 96/;

my $mw = new MainWindow;
my $lb = $mw->Listbox(-selectmode => 'single',
                   );

$lb->pack(-side => 'left', -fill => 'both');

$lb->insert('end', sort @cursors);
$lb->bind('<Button-1>', 
     sub { $mw->configure(-background => $lb->get($lb->curselection));
+ });


$lb->grid( -row => 10, -column => 2, -columnspan => 1);

MainLoop();
[download]

Turns out, two lines - initialise $mw and call MainLoop(). The code executes without error and shows a main window containing a list.