#!/usr/bin/perl

use Tk;
use strict;
use warnings;

my $mw = new MainWindow;

my $b = $mw->Button(-text => 'Run')->pack();

my $id;
my $i;
$b->bind('<ButtonPress-1>' => sub { $id = $mw->repeat(0, sub {print ++$i}) } );
$b->bind('<ButtonRelease-1>' => sub { $id->cancel() } );

MainLoop();