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

my $mw = MainWindow->new();

my $lb = $mw->Scrolled("Listbox", -scrollbars => 'e',)->pack(
    -side => 'left',
    -fill => 'y'
);

for my $key ("first", "second", "third", "fourth") {
    $lb->insert('end', $key);
}

$lb->activate(0);
$lb->selectionSet(0);
$lb->focus();

$lb->bind('<x>', sub {down($lb, @_)});
$mw->bind('<e>', sub {up($lb, @_)});

MainLoop;


sub down {
    my ($lb) = @_;
    my @selItems = $lb->curselection();

    return if 1 != @selItems || $selItems[0] == $lb->size();

    my $item = $lb->get($selItems[0]);

    $lb->delete($selItems[0]);
    $lb->insert($selItems[0] + 1, $item);
    $lb->selectionSet($selItems[0] + 1);
}


sub up {
    my ($lb) = @_;
    my @selItems = $lb->curselection();

    return if 1 != @selItems || $selItems[0] == 1;

    my $item = $lb->get($selItems[0]);

    $lb->delete($selItems[0]);
    $lb->insert($selItems[0] - 1, $item);
    $lb->selectionSet($selItems[0] - 1);
}