#!/usr/local/bin/perl -w
#
# Simple Tk script to create a button that prints "Hello, world".  Click on 
# the button to terminate the program.
# 
# The first line below imports the Tk objects into the application, the second
# line creates the main window, the third through sixth lines create the button
# and defines the code to execute when the button is pressed, the seventh line
# asks the packer to shrink-wrap the application's main window around the
# button, and the eight line starts the event loop.

use Tk;
$MW = MainWindow->new;
$hello = $MW->Button(
    -text    => 'Hello, world', 
    -command => sub {print STDOUT "Hello, world\n"; exit;},
);
$hello->pack;
MainLoop;