The source code

    Ext.onReady(function(){
        Ext.Direct.addProvider(Ext.app.REMOTING_API);

        var tree = new Ext.tree.TreePanel({
            width: 400,
            height: 400,
            autoScroll: true,
            renderTo: document.body,
            root: {
                id: 'root',
                text: 'Root'
            },
            loader: new Ext.tree.TreeLoader({
                directFn: TestAction.getTree
            }),
            fbar: [{
                text: 'Reload root',
                handler: function(){
                    tree.getRootNode().reload();
                }
            }]
        });
    });