function addLoadEvent(func) {
  var oldonload = window.onload;
  if (typeof window.onload != 'function') {
	window.onload = func;
  } else {
	window.onload = function() {
	  oldonload();
	  func();
	}
  }
}

function prepareGallery() {
	if (!document.getElementsByTagName) return false;
	if (!document.getElementById) return false;
	if (!document.getElementById("imageGallery")) return false;
	var gallery = document.getElementById("imageGallery");
	var links = gallery.getElementsByTagName("a");
	for (var i = 0; i < links.length; i++) {
		links[i].onclick = function() {
			return showPic(this);
		}
	}
}

function showPic(whichpic) {
	if (!document.getElementById("placeholder")) return true;
	var source = whichpic.getAttribute("href");
	var placeholder = document.getElementById("placeholder");
	placeholder.setAttribute("src",source);
	var text = whichpic.getAttribute("title");
	// keep original title if photo doesn't have a caption
	if (text == "") {
		var text = "Select thumbnail above to view larger image";
	}
	var description = document.getElementById("caption");
	description.firstChild.nodeValue = text;
	return false;
}

addLoadEvent(prepareGallery);