#!/usr/bin/perl -w
use strict;
use Tk;

my $main = MainWindow->new;

my $list = $main->Scrolled('Listbox', -scrollbars => 'e',
                           -selectmode => 'single')->pack;

foreach my $i (1..100) {
   $list->insert('end', "item $i");
}

my $button = $main->Button(-text => "Scroll to Bottom of List",
                           -command => \&scroll_to_bottom)->pack;
MainLoop;

sub scroll_to_bottom {
   my ($first, $last) = $list->Subwidget("yscrollbar")->get;

   # set to end of list
   my $winsize = $last - $first;
   $first = 1.0 - $winsize;
   $last = 1.0;
   $list->Subwidget("yscrollbar")->set($first, $last);
}