use Tk;
use Tk::DialogBox;

my $mw = new MainWindow();
my $dialog = $mw->DialogBox(-title => "Blah",
                            -buttons => ["OK"]);
my $content_window = $dialog->add("Text")->pack();
$dialog->Show();
my $content = $content_window->Contents();
$mw->destroy();
MainLoop;
print $content;