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

use Tk;

my %widget;
my $text;
my $temp = 1;

$widget{main} = MainWindow->new();
$widget{frame} = $widget{main}->Frame(-width => 65, -height => 20);
$widget{frame}->packPropagate(0);
$widget{frame}->pack(-side => 'top');
$widget{label} = $widget{frame}->Label(-textvariable => \$text);
$widget{exit} = $widget{main}->Button(-text => 'quit', -command => sub { $widget{main}->destroy(); });
$widget{change} = $widget{main}->Button(-text => 'change', -command => \&change);
$widget{entry} = $widget{frame}->Entry(-textvariable => \$text);

$widget{label}->pack(-side => 'top');
$widget{exit}->pack(-side => 'right');
$widget{change}->pack(-side => 'left');

MainLoop();

sub change {
if($temp) {
    $widget{label}->packForget();
    $widget{entry}->pack(-side => 'top');
    $temp = 0;
} else {
    $widget{entry}->packForget();
    $widget{label}->pack(-side => 'top');
    $temp = 1;
    }
}