use strict;
use Tk;

my $mw = MainWindow->new();

# Create the vertical Scrollbar
my $scrollbar = $mw->Scrollbar();
my $lb = $mw->Listbox(-yscrollcommand => ['set' => $scrollbar]);

# Configure the Scrollbar to talk to the Listbox widget
$scrollbar->configure(-command => ['yview' => $lb]);

# Pack the Scrollbar first so that it doesn't disappear when we resize
$scrollbar->pack(-side => 'right', -fill => 'y');
$lb->pack(-side => 'left', -fill => 'both');

my %cb;
foreach ( qw/a b c d e f g h/ ) {
   $lb->Checkbutton(-text => "$_", -variable => \$cb{"cb$_"}) ->
       pack(-side => 'top');
}

MainLoop();