#! /usr/bin/perl

use strict;
use warnings;
use Tk;

my $mw = MainWindow->new();
$mw->Button(-text => 'offen', -command => \&topl)->pack();

MainLoop;

sub topl{
  my $toplevel = $mw->Toplevel(-title => 'Test');
  local $SIG{ALRM} = sub {$toplevel->destroy()};
  alarm(6);
}