To reproduce: add a RadTreeView and a timer. Use the following code:

BindingList<Item> list = new BindingList<Item>();

public Form1()
{
    InitializeComponent();
    this.radTreeView1.TreeViewElement.CreateNodeElement += TreeViewElement_CreateNodeElement;
   
    for (int i = 0; i < 10; i++)
    {
        list.Add(new Item(Guid.NewGuid().ToString(), "Node" + i));
    }

    this.radTreeView1.DataSource = list;
    this.radTreeView1.DisplayMember = "Title";
    this.radTreeView1.ValueMember = "UniqueIdentifier";

    this.radTreeView1.TreeViewElement.AutoSizeItems = true;
    this.timer1.Start();
}

void TreeViewElement_CreateNodeElement(object sender, Telerik.WinControls.UI.CreateTreeNodeElementEventArgs e)
{
    e.NodeElement = new CustomTreeNodeElement();
}

public class Item: System.ComponentModel.INotifyPropertyChanged
{
    public Item(string uniqueIdentifier, string title)
            {
                this._uniqueIdentifier = uniqueIdentifier;
                this._title = title;
            }

    public string UniqueIdentifier
            {
                get
                {
                    return this._uniqueIdentifier;
                }
                set
                {
                    this._uniqueIdentifier = value;
                    OnPropertyChanged("UniqueIdentifier");
                }
            }

    public string Title
            {
                get
                {
                    return this._title;
                }
                set
                {
                    this._title = value;
                    OnPropertyChanged("Title");
                }
            }

    public event PropertyChangedEventHandler PropertyChanged;

    protected virtual void OnPropertyChanged(string propertyName)
            {
                if (PropertyChanged != null)
                {
                    PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
                }
            }

    private string _uniqueIdentifier;
    private string _title;
}

public class CustomContentElement : TreeNodeContentElement
{
    StackLayoutElement nodeContentContainer;
    LinePrimitive lineElement;
    LightVisualElement idElement;
    RadTextBoxControlElement textBoxElement;

    protected override Type ThemeEffectiveType
            {
                get
                {
                    return typeof(TreeNodeContentElement);
                }
            }

    protected override void InitializeFields()
            {
                base.InitializeFields();
                this.Margin = new Padding(5, 5, 5, 5);

                this.StretchHorizontally = true;
            }

    public override void Synchronize()
    {
        this.DrawFill = true;

        TreeNodeElement treeNodeElement = this.NodeElement;
        RadTreeNode node = treeNodeElement.Data;
        Item dataItem = (Item)node.DataBoundItem;
        if (dataItem != null)
        {
            this.idElement.Text = string.Empty + dataItem.UniqueIdentifier;

            this.textBoxElement.Text = string.Empty + dataItem.Title;
        }
    }

    protected override void CreateChildElements()
            {
                nodeContentContainer = new StackLayoutElement();
                nodeContentContainer.Orientation = Orientation.Vertical;
                nodeContentContainer.StretchHorizontally = true;
                nodeContentContainer.StretchVertically = false;

                idElement = new LightVisualElement();
                idElement.ShouldHandleMouseInput = false;
                idElement.NotifyParentOnMouseInput = true;
                idElement.StretchVertically = false;
                this.nodeContentContainer.Children.Add(idElement);

                lineElement = new LinePrimitive();
                lineElement.BackColor = Color.Black;
                lineElement.Margin = new Padding(10, 0, 10, 0);
                lineElement.StretchVertically = false;
                this.nodeContentContainer.Children.Add(lineElement);

                textBoxElement = new RadTextBoxControlElement();
                textBoxElement.TextChanged += textBoxElement_TextChanged;
                textBoxElement.Margin = new Padding(20, 3, 20, 3);
                textBoxElement.StretchVertically = false;
                this.nodeContentContainer.Children.Add(textBoxElement);

                this.Children.Add(nodeContentContainer);
            }

    private void textBoxElement_TextChanged(object sender, EventArgs e)
    {
        RadTextBoxControlElement tb = sender as RadTextBoxControlElement;
        CustomContentElement contentElement = tb.Parent.Parent as CustomContentElement;
        Item item = contentElement.NodeElement.Data.DataBoundItem as Item;
        if (item.Title != tb.Text)
        {
            item.Title = tb.Text;
        }
    }
}

public class CustomTreeNodeElement : TreeNodeElement
{
    protected override TreeNodeContentElement CreateContentElement()
    {
        return new CustomContentElement();
    }

    protected override Type ThemeEffectiveType
    {
        get
        {
            return typeof(TreeNodeElement);
        }
    }
}

private void timer1_Tick(object sender, EventArgs e)
{
    foreach (Item item in list)
    {
        item.Title = "Node " + DateTime.Now.ToLongTimeString();
    }
}