var prevBox = new Array("", "");
var prevSrc = new Array("", "");

function showBox(menu, element, on, off) {
	if(prevBox[menu] != "") {
		document.getElementById("display_" + prevBox[menu]).style.display = "none";
		document.getElementById("head_" + prevBox[menu]).src = prevSrc[menu];
	}
	document.getElementById("display_" + element).style.display = "block";
	document.getElementById("head_" + element).src = on;
	prevBox[menu] = element;
	prevSrc[menu] = off;
}

<!--- Pop Up Window Function --->

function popWindow (address) {
	window.open ("imageHtmls/"+address,"popWindow","menubar=1,resizable=0,width=650,height=455"); 
}