#!/usr/bin/perl

use strict;
use warnings;

use threads;
use threads::shared;
use Tk;

my $xxx:shared='';
my $thread = threads->create( \&search_file );
$thread->detach;

my $mw = tkinit();
$mw->Label( -text => 'hallo' )->pack;
$mw->Entry( -textvariable => \$xxx )->pack;

MainLoop;

sub search_file {
    my $counter = 0;
    for (;;) {
        $counter++;
        $xxx = $counter;
        sleep 1;
    }
}