#!/usr/bin/perl

use 5.010;
use strict;
use warnings;

use Tk;
use Tk::Pane;

my @stuff = map { ucfirst lc } keys %ENV;

my $mw = MainWindow->new;

my $pane =
  $mw->Scrolled( 'Pane', -scrollbars => 'osoe' )
  ->pack( -expand => 1, -fill => 'both' );

$mw->repeat(
    1000,
    sub {
        $pane->Label( -text => $stuff[ rand @stuff ] )->pack;
    }
);
MainLoop;