#!/usr/bin/perl
use warnings;
use strict;
use threads;
use threads::shared;

my $ret:shared = 0;
my $die:shared = 0;;

my $val = 0;

#create thread before any tk code is called
my $thr = threads->create( \&worker );

use Tk;

my $mw = MainWindow->new();
$mw->protocol('WM_DELETE_WINDOW' => sub { &clean_exit }); 

my $label = $mw->Label(
         -width => 50,
         -textvariable => \$val )->pack();

my $button;
$button = $mw->Button(
         -text => 'Stop thread',
	 -command => sub{
	    $button->configure(-state=>'disabled');
	    $die = 1;
            $thr->join;
	  },
     )->pack();

 
my $timer = $mw->repeat(10,sub{
              $val = $ret;
             });

MainLoop;

sub clean_exit{
 $timer->cancel;

my @running_threads = threads->list;
if (scalar(@running_threads) < 1){print "\nFinished\n";exit}
  else{
     $die = 1;
     $thr->join;
     exit;
  }
}

# no Tk code in thread
sub worker {
   for(1..10){
     print "$_\n"; 
     $ret = $_;
     if($die){return}
     sleep 1; 
    }
   $ret = 'thread done, ready to join';
   print "$ret\n";
}