Even simpler than Dialog, but still quite usable is the messageBox.

#!/usr/bin/perl
use warnings;
use strict;
use Tk;

my $mw = tkinit;

$mw->Button(-text=>'Press Me',
            -command => sub{
                  my $message = localtime;
                  &send_message( $message) }
            )->pack;
MainLoop;

sub send_message{
  my $message = shift;
  $mw->messageBox(
            -background => 'lightyellow',
            -icon       => 'error',
            -message    => $message,
            -type       => 'OK'
        );
}
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