function highlightImg(topicName) {
	var imgSrc = document.images[topicName].src;
	if(imgSrc.indexOf("_high.gif") == -1) {
		document.images[topicName].src = imgSrc.substring(0,imgSrc.indexOf(".gif")) + "_high.gif";
	}
}

function resetImg(topicName) {
	var imgSrc = document.images[topicName].src;
	if(imgSrc.indexOf("._high.gif") == -1) {
		document.images[topicName].src = imgSrc.substring(0,imgSrc.indexOf("_high.gif")) + ".gif";
	}
}