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

my $mw = Tk::MainWindow->new(-title => 'Listbox');

my @array = (1..10);

my $lb = $mw->Scrolled('Listbox',
         -listvariable=> \@array,
        )->pack();

my $b = $mw->Button(-text => 'update',
        -command => \&update
          )->pack();

MainLoop;

sub update {
  @array = map{"$_.a"}(1..10);
  push @array,11;
  $lb->update;
}
[download]