my $canvas = $mw->Canvas(-width  => '350',
                     -height => '350',
                     -bg     => '#FFFFFF',
                        )
                  ->pack();
$canvas->bind("<1>" => sub {
   my $e = $canvas->XEvent;
   my($x, $y) = ($canvas->canvasx($e->x),
                 $canvas->canvasy($e->y));
   $canvas->createLine($x, $y, ($x+50), ($y+50));