$canvas{'ref'}->CanvasBind("<1>", [ \&print_xy, Ev('x'), Ev('y') ]); 

sub print_xy{
   my ($canv, $x, $y) = @_;
   print "(x,y) = ", $canv->canvasx($x), ", ", $canv->canvasy($y), "\n";   
}

##</code><code>##

         $canvas{'ref'}->CanvasBind("<1>" =>
                  sub{
                        my $screenX = Ev('x');
                        my $screenY = Ev('y');
                        my $x = $canvas{'ref'}->canvasx($screenX);
                        my $y = $canvas{'ref'}->canvasy($screenY);
                        print "($x,$y)\n";
                     });