<svg width="800" height="600" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink">
<defs>
    <marker id="markerStart" viewBox="0 0 10 10" markerWidth="1" markerHeight="2" refX="5" refY="5" markerUnits="strokeWidth">
        <rect width="10" height="10" fill="red" stroke="none"/>
    </marker>
    <marker id="markerMiddle" viewBox="0 0 10 10" markerWidth="2" markerHeight="2" refX="5" refY="5" markerUnits="strokeWidth">
        <circle cx="5" cy="5" r="5" fill="green" stroke="none"/>
    </marker>
    <marker id="markerEnd" viewBox="0 0 10 10" markerWidth="2" markerHeight="2" refX="5" refY="5" markerUnits="strokeWidth">
        <path d="M 5 0 L 10 10 L 0 10 Z" fill="blue" stroke="none"/>
    </marker>
</defs>

<script>
if (window.layoutTestController)
    layoutTestController.waitUntilDone();

window.setTimeout("clickNow()", 0);

function clickNow() {
    if (window.eventSender) {
        eventSender.mouseMoveTo(150, 135);
        eventSender.mouseDown();
        eventSender.mouseUp();
    }

    if (window.layoutTestController) {
        layoutTestController.notifyDone();
    }
}

function mouseHandler(evt)
{
    var marker = document.getElementById("markerStart");
    marker.setAttribute("markerWidth", "2");
}
</script>

<g onclick="mouseHandler()">
    <path fill="none" stroke="black" stroke-width="8" marker-start="url(#markerStart)" marker-mid="url(#markerMiddle)" marker-end="url(#markerEnd)" d="M 130 135 L 180 135 L 180 185"/>
</g>
</svg>