function expandContract(obj) {
	node  = obj.childNodes[1];
	plus  = "url(/~mmap/images/plus1.gif)";
	minus = "url(/~mmap/images/minus.gif)";
	
	node.style.display = (node.style.display != "block") ? "block" : "none";
	obj.style.backgroundImage = (obj.style.backgroundImage != minus) ? minus : plus;
}