#!/usr/bin/perl

# http://perlmonks.org/?node_id=1191710

use strict;
use warnings;
use Tk;

my $count = 0;
my $mw = MainWindow -> new;
$mw -> Label(-text => 'Counter') ->pack();
$mw -> Label(-textvariable => \$count ) ->pack();
$mw -> Button( -text    => 'Count', -command => sub { $count++ } ) ->pack();

MainLoop;