#!/usr/bin/perl

##########
use Tk;
use strict;

my $mw=tkinit;
my $c=$mw->Scrolled('Canvas',
 -width=>400,
 -height=>400,
 -bg=>'red',
 -scrollregion=>[0,0,1000,1000],
 -scrollbars=>'se')->pack(-expand=>1, -fill=>'both');

$c->create('rect',&n) for (0..40);

my $id = $mw->repeat(100,sub{
 $c->xviewScroll(1,'units');
 $c->yviewScroll(1,'units');
});
$mw->after(10000, sub{$id->cancel});
MainLoop;

sub n
{
  my ($x1,$y1) = ( rand(1000), rand(1000) );
  my ($x,$y) = ($x1/2,$y1/2);
  return ($x,$y,$x1,$y1);
}