use Tk;

my $mw     = MainWindow->new;
my $c      = $mw->Scrolled('Canvas')->pack();
my $canvas = $c->Subwidget('canvas');
$canvas->CanvasBind("<Button-1>", [ \&print_xy, Ev('x'), Ev('y') ]);
sub print_xy {
  my ($canv, $x, $y) = @_;
  print "(x,y) = ",$canv->canvasx($x),", ",$canv->canvasy($y),"\n";
}