var path = "/images/";

var offimg = new Image();
offimg.src = path + "spacer.gif";
var onimg = new Image();
onimg.src = path + "green_arrrow.gif";
var redonimg = new Image();
redonimg.src = path + "red_arrow.gif";

function switchOn(imgName) {
	if(document.getElementById('eventDisplay') ==null) {
		if (document.images) document[imgName].src = onimg.src;
	} else {
		if (document.images) document[imgName].src = redonimg.src;
	}
}

function switchOff(imgName) {
	if (document.images) document[imgName].src = offimg.src;
}