#!/usr/local/bin/perl -w 

use 5.005; 
use Tk; 
use Tk::widgets qw/Dialog/; 
use subs qw/build_menubar fini/; 
use vars qw/$MW $VERSION/; 
use strict; 

$MW = MainWindow->new(); 
$MW->geometry('640x100');

my $menubar = build_menubar; 
my $Body = $MW->Frame(-background => 'cyan')->pack(
  -expand => 1,
  -fill   => 'both',
); 

MainLoop; 

sub build_menubar { 
  my $menubar = $MW->Menu; 
  my $file    = $menubar->cascade(-label => '~File'); 

  $MW->configure(-menu => $menubar); 
  $file->command(-label => "Print Text", -command => \&PrintText);
  $file->command(-label => "Quit",       -command => \&fini); 

  return $menubar;
}

sub PrintText{
  my $lbl = $Body->Label(
    -text       => "This is new text",
    -background => 'red',
    #-width      => '100',  # This would be 100 _characters_
    #-height     => '100',  # And this 100 _lines_
  )->pack(
    -fill   => 'both',
    -expand => 1,
  );
}

sub fini { exit; }