var ie = document.all;
var ns = document.getElementById && !ie;

document.getElementById('tree').onclick=function(e)
{
    var e = ns ? e : event;
    var obj = ns ? e.target : event.srcElement;

    if (obj.tagName == "P" && obj.nextSibling.tagName == "DIV") {
        var div = obj.nextSibling;
        if (div.style.display != "block") {
            div.style.display = "block";
            obj.setAttribute("class", "close");
            obj.setAttribute("className", "close");
        }
        else {
            div.style.display = "none";
            obj.setAttribute("class", "open");
            obj.setAttribute("className", "open");
        }
    }
}