Mouse dragging

<?xml version="1.0" standalone="no"?>
<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN"
"http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
<svg width="428px" height="300px" viewBox="0 0 428 300" xmlns="http://www.w3.org/2000/svg">
<circle id="circle" cx="214" cy="150" r="15" fill="olivedrab"/>
<rect x="0" y="0" width="428" height="300" opacity="0" onmousemove="moveGraphics(evt)"/>
<script type="text/ecmascript"><![CDATA[
 var circleobj = document.getElementById("circle");
 function moveGraphics(evt) {
 circleobj.setAttributeNS(null, "cx", evt.clientX);
 circleobj.setAttributeNS(null, "cy", evt.clientY);
}
]]></script>
</svg>