#!/usr/bin/perl --
use strict; use warnings;
use Tk;
my $mw = tkinit();
my $l = $mw->Label->pack( -side => 'bottom' );
$mw->Button(
    -command => [ \&ralala, $l ],
)->pack;
MainLoop();
sub ralala {
    my( $l ) = @_;
    $l->configure( -text =>  join "\n",  1 .. rand 4 );
}