function toggleClass(obj_id) {
	if (document.getElementById) {
		var obj = document.getElementById(obj_id);
		if (obj.className == "esconder") {
			obj.className = "esconder escondido";
			return true;
		} else {
			obj.className = "esconder";
			return true;
		}
	}
}

// version 2:

function toggleClass_v2(obj_id, the_className) {
	if (document.getElementById) {
		var obj = document.getElementById(obj_id);
		if (obj.className.indexOf(the_className) == -1) {
			obj.className = obj.className+the_className;
			return true;
		} else {
			the_class_names = obj.className.split(" ");
			obj.className = the_class_names[0];
			return true;
		}
	}
}