use Tk;
use strict;
use warnings;

my $main = new MainWindow();
my $canvas = $main->Scrolled('Canvas',
                              -scrollbars => 'se', 
                              -height => 400, 
                              -width => 400,
)->pack;
$canvas->createOval(100,100,500,500);

MainLoop;

##</code><code>##

$canvas->createText(…);