use warnings;
use strict;
use Tk;

my $mw = MainWindow->new (-title => "editor");
my $text = $mw->Scrolled
    ('Text', -font => 'normal', -wrap => 'word', -scrollbars => 'e',);
$text->pack ();
$mw->Button (-text => "open file", -command => \&openFile)->pack ();
    
MainLoop ();

sub openFile {
    my @filetypes = (
            ['Text', '.txt',  'TEXT'],
            ['Text', '.txt',  'TEXT'],
        );

    my $currentFile = $text->getOpenFile
        (-defaultextension => '.txt', -filetypes => \@filetypes);
}

##</code><code>##

use Storable;

# Load persistent stuff
my $persistRef = retrieve ('config') if -e 'config';

# Use stuff
my $text = $persistRef->{text} || '';

# ...
$persistRef->{text} = $text;

# Save stuff
store $persistRef, 'config';