function toggle2(evt) {
    	var tmpEvt = evt || window.event;
	    var obj = tmpEvt.srcElement || tmpEvt.target;

        var elm = document.getElementById('u'+obj.id.substring(1));
        if (elm.style.display == "none") {
            elm.style.display = "block";
        } else {
          elm.style.display = "none";
        }
    }

function createNode(item) {
    var elm = document.createElement("p");
    elm.id = "p"+item.id;
    elm.setAttribute("class","group_italic");
    elm.style.cursor="pointer";
    elm.style.color="#218384";
    elm.style.textDecoration="underline";
    elm.onclick=toggle2;
    elm.innerHTML=item.name;
    document.getElementById("contentCell").appendChild(elm);
    createCategory(item);
}

function createCategory(item) {
    var elm = document.createElement("ul");
    elm.id = "u"+item.id;
    elm.style.display="none";
    for (var i=0; i<item.children.length; i++) {
        elm.appendChild(getCourse(item.children[i][0],item.children[i][1]));
    }
    document.getElementById("contentCell").appendChild(elm);    
}

function getCourse(link, text) {
    var elm = document.createElement("li");
    elm.innerHTML="<a href="+link+">"+text+"</a>";
    return elm;
}

function CategoryItem(id, name) {
    this.id = id;
    this.name = name;
    this.children = null;
    return this;
}