#!/usr/bin/perl -w

use strict;
use Tk;

my $Main = MainWindow->new();

my $text = "foobar";

my $Entry = $Main->
    Entry( -textvariable => \$text )->
    pack( -expand => 1, -fill => 'x' );

my $Button = $Main->
    Button( -text => 'Clear',
         -width => 20,
         #choose one of the following
         #-command => sub { $text = '' }
         #-command => sub { $Entry->delete( 0, 'end' ) }
         )->pack();

MainLoop;