#!/usr/bin/perl

use strict;
use warnings;
use Tk;

my $number = 1;
my $mw = MainWindow->new;

$mw->waitVisibility;

my $label = $mw->Label(-textvariable =>\$number)->pack();

$mw->repeat(1000, [sub{ ${$_[0]}++; $label->update; }, \ $number] );

$mw->waitVisibility;