Source code in the perl programming language

use strict;
use warnings;
use Tk;

my $main = MainWindow->new;
$main->Label(-text => 'Goodbye, World')->pack;
MainLoop();


use strict;
use warnings;
use Tk;

my $main = MainWindow->new;
$main->Button(
  -text => 'Goodbye, World',
  -command => \&exit,
)->pack;
MainLoop();


use strict;
use warnings;
use Gtk2 '-init';

my $window = Gtk2::Window->new;
$window->set_title('Goodbye world');
$window->signal_connect(
  destroy => sub { Gtk2->main_quit; }
);

my $label = Gtk2::Label->new('Goodbye, world');
$window->add($label);

$window->show_all;
Gtk2->main;


use strict;
use warnings;
use QtGui4;

my $app = Qt::Application(\@ARGV);
my $label = Qt::Label('Goodbye, World');
$label->show;
exit $app->exec;