function prepareCategoryExpanders() {
	if (!document.getElementsByClassName) return false;
	var categoryDivs = document.getElementsByClassName("category");
	for (var i = 0; i < categoryDivs.length; i++) {
		var categoryHeadings = categoryDivs[i].getElementsByTagName("div");
		categoryHeadings[0].onclick = function() {
			if (!this.getAttribute("id")) return false;
			var headingId = this.getAttribute("id");
			var idNumber = headingId.replace("categoryhead", "")
			if (!document.getElementById("categorylist" + idNumber)) return false;
			var subList = document.getElementById("categorylist" + idNumber);
			if (subList.style.display == "block") {
				subList.style.display = "none";
				this.style.background = "#e6e6e6 url(../bgimages/expand.png) top left no-repeat";
			}
			else {
				subList.style.display = "block";
				this.style.background = "#e6e6e6 url(../bgimages/contract.png) top left no-repeat";
			}
		}
	}
	return true;
}

addOnLoadEvent(prepareCategoryExpanders);