It doesn't seem to work for me. I want to show the message which is stored in $message when I click the rectangle. I modified the code this way.

$svg->rectangle(
                x =>$x1,
                y =>$y1,
                width  => $x2,
                height => $y2,
                style => {
                        'fill'           => 'rgb(0, 0, 128)',
                        'stroke'         => 'black',
                        'stroke-width'   =>  1,
                        'stroke-opacity' =>  1,
                        'fill-opacity'   =>  1,
                },
        );
$rectangle->attrib(onclick=>q{alert($message);});
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Please correct me if I am wrong