<defs>
<g id = "myClass">

<script type="text/ecmascript" ><![CDATA[

// displays yellow flash
function showFlash(evt) {
flash = evt.target.ownerDocument.getElementById("flash");
flash.setAttributeNS(null, "visibility", "visible");
return;
}
// hides yellow flash
function hideFlash(evt) {
flash = evt.target.ownerDocument.getElementById("flash");
flash.setAttributeNS(null, "visibility", "hidden");
}

]]></script>

<circle id="flash" cx="275" cy="200" r="30"
style="fill:rgb(255,255,0);stroke:url(#red-yellow-red);stroke-width:5" visibility="hidden"/>

</g>
</defs>