The source code

    var TreeTest = function(){
        // shorthand
        var Tree = Ext.tree;

        return {
            init : function(){
                // yui-ext tree
                var tree = new Tree.TreePanel({
                    animate:true,
                    autoScroll:true,
                    loader: new Tree.TreeLoader({dataUrl:'get-nodes.php'}),
                    containerScroll: true,
                    border: false,
                    height: 300,
                    width: 300
                });

                // add a tree sorter in folder mode
                new Tree.TreeSorter(tree, {folderSort:true});

                // set the root node
                var root = new Tree.AsyncTreeNode({
                    text: 'Ext JS',
                    draggable:false, // disable root node dragging
                    id:'src'
                });
                tree.setRootNode(root);

                // render the tree
                tree.render('tree');
                root.expand(false, /*no anim*/ false);
                tree.bodyFocus.fi.setFrameEl(tree.el);
                tree.getSelectionModel().select(tree.getRootNode());
                tree.enter.defer(100, tree);
            }
        };
    }();

    Ext.EventManager.onDocumentReady(TreeTest.init, TreeTest, true);