#!/usr/bin/perl

use Tk;

use strict;
use warnings;

my $count = 0;
my $count_on = 0;

my $window = MainWindow->new;
$window->title("My Example");
$window->Label(-textvariable => \$count )->pack;
$window->Button(
	-text => "Start",
	-command => sub {$count_on = 1},
	)->pack;
$window->Button(
	-text => "Stop",
	-command => sub {$count_on = 0},
	)->pack;

my $timer = Tk::After->new($window, 1000, 'repeat', sub { $count++ if $count_on });

MainLoop;