Steps to reproduce: 
1. Add RadTreeView with few items 
2. Apply custom filtering 
3. In order to remove the custom filtering and return the default filtering, set the FilterPredicate to null. 
As a result, it is thrown an exception. 

Workaround: 
1. Save the default filter predicate before applying the custom filtering 
2. Clear filter descriptors and set the FilterPredicate property to stored default filter predicate

In the attachments can be found a sample application demonstrating the issue and the workaround 

To reproduce:
- Add a lot of nodes to the tree (scrollbars must appear).
- Use the following code to add nodes:
public RadForm1()
{
    InitializeComponent();
    radTreeView1.AllowEdit = true;
    RadContextMenu menu = new RadContextMenu();
    RadMenuItem add = new RadMenuItem();
    add.Click += add_Click;
    add.Text = "add";
    menu.Items.Add(add);
    radTreeView1.RadContextMenu = menu;

}
void add_Click(object sender, EventArgs e)
{
    RadTreeNode node = radTreeView1.SelectedNode;

    var newNode = node.Nodes.Add("new node");
    node.Expanded = true;
    radTreeView1.SelectedNode = newNode;
    radTreeView1.BeginEdit();
}
- Add a node and scroll

Workaround:
public RadForm1()
{
    InitializeComponent();
    radTreeView1.TreeViewElement.VScrollBar.Scroll += VScrollBar_Scroll;
    radTreeView1.MouseWheel += TreeViewElement_MouseWheel;
}

void TreeViewElement_MouseWheel(object sender, MouseEventArgs e)
{
    var radTreeView = sender as RadTreeView;
    if (radTreeView.IsEditing)
    {
        radTreeView.EndEdit();
    }
}

void VScrollBar_Scroll(object sender, ScrollEventArgs e)
{
    var radTreeView = (sender as RadScrollBarElement).ElementTree.Control as RadTreeView;
    if (radTreeView.IsEditing)
    {
        radTreeView.EndEdit();
    }
}

Start dragging a node and scroll using the mouse wheel. While scrolling, drop the node. 

Please refer to the attached sample project and follow the steps: 

If you execute my code sample and try this sequence, you will see my problem:
1- start the application
2- select "test1" on the grid => you see "fonction XX of test1" in the treeview (that's correct)
3- select "test2" on the grid => you see "fonction XX of test2" in the treeview (that's correct)
4- expand all nodes in the treeview
5- uncheck "fonction 31 of test2" in the treeview
6- select "test1" on the grid => you have the error message. On the grid, we have "test1" selected and on the treeview we have "test2".
Note that the problem appears only when checking a node in the treeview on a second level. If you follow this procedure, you will have no problem :
1- restart the application
2- select "test1" on the grid => you see "fonction XX of test1" in the treeview (that's correct)
3- select "test2" on the grid => you see "fonction XX of test2" in the treeview (that's correct)
4- uncheck "fonction 30 of test2" in the treeview
5- select "test1" on the grid => you will have no error. On the grid, we have "test1" selected and on the treeview we have "test1".
6- select "test2" on the grid => you will have no error. On the grid, we have "test2" selected and on the treeview we have "test2" with "fonction 30 of test2" unchecked.

Workaround: in order to synchronize the current row in RadGridView is to change the RadTreeView.DataSource in the RadGridView.CurrentRowChanged event.

Please refer to the attached gif file.

Workaround: set the Enabled property to false at run time.

Workaround: create a custom TreeNodeContentElement and override the Synchronize method

public class MyTreeNodeContentElement : TreeNodeContentElement
{
    protected override Type ThemeEffectiveType
    {
        get
        {
            return typeof(TreeNodeContentElement);
        }
    }

    public override void Synchronize()
    {
        TreeNodeElement treeNodeElement = NodeElement;

        if (treeNodeElement == null || treeNodeElement.Data == null || treeNodeElement.Data.TreeViewElement == null || treeNodeElement.Data.Text == null)
        {
            return;
        }

        this.Text = treeNodeElement.Data.Text;
    }

}

public class MyTreeNodeElement : TreeNodeElement
{
    protected override TreeNodeContentElement CreateContentElement()
    {
        return new MyTreeNodeContentElement();
    }

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

public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();

        this.radTreeView1.AllowEdit = true;

        this.radTreeView1.DisplayMember = "name";
        this.radTreeView1.ParentMember = "pid";
        this.radTreeView1.ChildMember = "id";
        this.radTreeView1.DataSource = this.GetSampleData();

        this.radTreeView1.CreateNodeElement += radTreeView1_CreateNodeElement;
        this.radTreeView1.ValueChanged += radTreeView1_ValueChanged;
    }

    private void radTreeView1_CreateNodeElement(object sender, Telerik.WinControls.UI.CreateTreeNodeElementEventArgs e)
    {
        e.NodeElement = new MyTreeNodeElement();
    }

    private void radTreeView1_ValueChanged(object sender, Telerik.WinControls.UI.TreeNodeValueChangedEventArgs e)
    {
       this.UpdateDb();
    }

    private void UpdateDb()
    {
        this.radTreeView1.DataSource = null;
        DataTable dt = this.GetSampleData();
        this.radTreeView1.DataSource = dt;
    }

    private DataTable GetSampleData()
        {
            DataTable dt = new DataTable();

            DataColumn dc = new DataColumn();
            dc.ColumnName = "id";
            dc.DataType = typeof(int);
            dt.Columns.Add(dc);

            DataColumn dc1 = new DataColumn();
            dc1.ColumnName = "name";
            dc1.DataType = typeof(string);
            dt.Columns.Add(dc1);

            DataColumn dc2 = new DataColumn();
            dc2.ColumnName = "pid";
            dc2.DataType = typeof(int);
            dt.Columns.Add(dc2);

            DataRow dr = dt.NewRow();
            dr[0] = 0;
            dr[1] = "My Computer";
            dr[2] = DBNull.Value;
            dt.Rows.Add(dr);

            dr = dt.NewRow();
            dr[0] = 1;
            dr[1] = @"C:\";
            dr[2] = 0;
            dt.Rows.Add(dr);

            dr = dt.NewRow();
            dr[0] = 2;
            dr[1] = @"D:\";
            dr[2] = 0;
            dt.Rows.Add(dr);

            dr = dt.NewRow();
            dr[0] = 3;
            dr[1] = "Program Files";
            dr[2] = 1;
            dt.Rows.Add(dr);

            dr = dt.NewRow();
            dr[0] = 4;
            dr[1] = "Microsoft";
            dr[2] = 3;
            dt.Rows.Add(dr);

            dr = dt.NewRow();
            dr[0] = 5;
            dr[1] = "Telerik";
            dr[2] = 3;
            dt.Rows.Add(dr);

            dr = dt.NewRow();
            dr[0] = 6;
            dr[1] = "WINDOWS";
            dr[2] = 1;
            dt.Rows.Add(dr);

            return dt;
        }
}

To reproduce: select a node and click the button. Note: it may be necessary to perform this several times.

public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();
    }

    private List<DataObject> GetDataList()
    {
        var ret = new List<DataObject>();

        ret.Add(new DataObject() { Node = "A", Parent = null });
        ret.Add(new DataObject() { Node = "B", Parent = "A" });
        ret.Add(new DataObject() { Node = "C", Parent = "B" });
        ret.Add(new DataObject() { Node = "D", Parent = "B" });

        return ret;
    }
    
    private void button1_Click(object sender, EventArgs e)
    {
        radTreeView1.Nodes.Clear(); 
        radTreeView1.DisplayMember = "Node";
        radTreeView1.ChildMember = "Node";
        radTreeView1.ParentMember = "Parent";
        radTreeView1.DataSource = GetDataList();
        radTreeView1.ExpandAll();
    }
}

public class DataObject
{
    public string Node { get; set; }

    public string Parent { get; set; }
}

Workaround: instead of clearing the nodes, set the DataSource property to null.

To reproduce:

private void Form1_Load(object sender, EventArgs e)
{ 
    this.radTreeView1.Nodes.Add("Node1");
    this.radTreeView1.Nodes.Add("Node2");
    this.radTreeView1.Nodes.Add("Node3");
    this.radTreeView1.Nodes.Add("Node4");
    this.radTreeView1.Nodes.Add("Node5");
    this.radTreeView1.Nodes.Add("Node6");
    this.radTreeView1.Nodes["Node1"].Nodes.Add("Node11");
    this.radTreeView1.Nodes["Node1"].Nodes.Add("Node12");
    this.radTreeView1.Nodes["Node1"].Nodes.Add("Node13");
    this.radTreeView1.Nodes["Node1"].Nodes.Add("Node14");
    this.radTreeView1.Nodes["Node2"].Nodes.Add("Node21");
    this.radTreeView1.Nodes["Node2"].Nodes.Add("Node22");
    this.radTreeView1.Nodes["Node2"].Nodes.Add("Node23");
    this.radTreeView1.Nodes["Node2"].Nodes.Add("Node24");
    this.radTreeView1.Nodes["Node3"].Nodes.Add("Node31");
    this.radTreeView1.Nodes["Node3"].Nodes.Add("Node32");
    this.radTreeView1.Nodes["Node3"].Nodes.Add("Node33");
    this.radTreeView1.Nodes["Node3"].Nodes.Add("Node34");
    this.radTreeView1.Nodes["Node4"].Nodes.Add("Node41");
    this.radTreeView1.Nodes["Node4"].Nodes.Add("Node42");
    this.radTreeView1.Nodes["Node4"].Nodes.Add("Node43");
    this.radTreeView1.Nodes["Node4"].Nodes.Add("Node44");
    this.radTreeView1.Nodes["Node5"].Nodes.Add("Node51");
    this.radTreeView1.Nodes["Node5"].Nodes.Add("Node52");
    this.radTreeView1.Nodes["Node5"].Nodes.Add("Node53");
    this.radTreeView1.Nodes["Node5"].Nodes.Add("Node54");
    this.radTreeView1.Nodes["Node6"].Nodes.Add("Node61");
    this.radTreeView1.Nodes["Node6"].Nodes.Add("Node62");
    this.radTreeView1.Nodes["Node6"].Nodes.Add("Node63");
    this.radTreeView1.Nodes["Node6"].Nodes.Add("Node64");
}

Workaround: add the nodes in the form's constructor.

Second workaround:  Me.RadTreeView1.TreeViewElement.Update(Telerik.WinControls.UI.RadTreeViewElement.UpdateActions.Reset)

To reproduce:
Add a RadTreeView ,add nodes, enable TriState, disable AutoCheckChildNodes and use this code:
void cxTreeView2_NodeCheckedChanging(object sender, RadTreeViewCancelEventArgs e)
{
    if (!cxTreeView2.AutoCheckChildNodes && cxTreeView2.CheckBoxes && cxTreeView2.TriStateMode)
    {
        cxTreeView2.TreeViewElement.NodeCheckedChanging -= cxTreeView2_NodeCheckedChanging;
        if (e.Node.CheckState == ToggleState.Indeterminate)
        {
            e.Cancel = true;
            e.Node.CheckState = ToggleState.On;
            CheckAllChildren(e.Node);
        }

        cxTreeView2.TreeViewElement.NodeCheckedChanging += cxTreeView2_NodeCheckedChanging;
    }
}

void CheckAllChildren(RadTreeNode parent)
{
    foreach (var node in parent.Nodes)
    {
        node.CheckState = ToggleState.On;
        CheckAllChildren(node);
    }
}

Click a top node two times and remove the mouse from the checkbox, it is now showing as Indetermined but the data item is on.

Workaround:
void cxTreeView2_NodeCheckedChanging(object sender, RadTreeViewCancelEventArgs e)
{
    if (!cxTreeView2.AutoCheckChildNodes && cxTreeView2.CheckBoxes && cxTreeView2.TriStateMode)
    {
        cxTreeView2.TreeViewElement.NodeCheckedChanging -= cxTreeView2_NodeCheckedChanging;
        if (e.Node.CheckState == ToggleState.Indeterminate)
        {
            e.Cancel = true;
            e.Node.CheckState = ToggleState.On;
            CheckAllChildren(e.Node);

            cxTreeView2.TreeViewElement.Update(RadTreeViewElement.UpdateActions.Reset);

        }

        cxTreeView2.TreeViewElement.NodeCheckedChanging += cxTreeView2_NodeCheckedChanging;
    }
}

void CheckAllChildren(RadTreeNode parent)
{
    foreach (var node in parent.Nodes)
    {
        node.CheckState = ToggleState.On;
        CheckAllChildren(node);
    }
}

To reproduce: use the attached sample project and follow the steps:

1. Filter by "Jo".
2. Press the "Refresh" button.
3. Press the "Clear Filter" button.

Note: if there is no applied filter when rebinding, the nodes order is correct. Please refer to the attached gif file.

Workaround: clear the filter before setting the DataSource property and restore ethe filter afterwards:
string filter = this.radTreeView1.Filter + "";
this.radTreeView1.Filter = "";
this.radTreeView1.DataSource = dt;
this.radTreeView1.DisplayMember = "Name";
this.radTreeView1.ValueMember = "Id";
this.radTreeView1.Filter = filter;

Error: "Object of type 'Telerik.WinControls.Enumerations.ToggleState' cannot be converted to type 'System.Boolean'."

To reproduce:

public Form1()
{
    InitializeComponent();

    List<Parent> dataItems = new List<Parent>();
    Parent currentParent;
    Child currentChild;
    List<Child> children;
    string parentId = string.Empty;
    string childId = string.Empty;
    for (int i = 1; i <= 5; i++)
    {
        parentId = Guid.NewGuid().ToString();

        children = new List<Child>();
        for (int j = 1; j < 5; j++)
        {
            childId = Guid.NewGuid().ToString();
            currentChild = new Child(childId, parentId, "SubNode." + i + "." + j, j % 2 == 0);
            children.Add(currentChild);
        }
        currentParent = new Parent(parentId, "Node." + i, i % 2 == 0,children);
        dataItems.Add(currentParent);
    }

    radTreeView1.DataSource = dataItems;
    radTreeView1.DisplayMember = "Title\\Name";
    radTreeView1.ChildMember = "Parent\\Children";
    radTreeView1.CheckedMember = "IsActive\\Status";
    radTreeView1.CheckBoxes = true;
}

public class Parent 
{
    public string ParentId { get; set; }

    public string Title { get; set; }

    public bool IsActive { get; set; }

    public List<Child> Children { get; set; }

    public Parent(string parentId, string title, bool isActive, List<Child> children)
    {
        this.ParentId = parentId;
        this.Title = title;
        this.IsActive = isActive;
        this.Children = children;
    }
}

public class Child
{
    public string ChildId { get; set; }

    public string ParentId { get; set; }

    public string Name { get; set; }

    public bool Status { get; set; }

    public Child(string childId, string parentId, string name, bool status)
    {
        this.ChildId = childId;
        this.ParentId = parentId;
        this.Name = name;
        this.Status = status;
    }
}

Workaround: Use a custom TypeConverter for the boolean properties:

public class ToggleStateConverter : TypeConverter
{
    public override bool CanConvertTo(ITypeDescriptorContext context, Type destinationType)
    {
        return destinationType == typeof(ToggleState);
    }

    public override object ConvertTo(ITypeDescriptorContext context, CultureInfo culture, object value, Type destinationType)
    {
        if (value is bool)
        {
            switch ((bool)value)
            {
                case true:
                    return ToggleState.On;
                case false:
                    return ToggleState.Off;
                default :
                    return ToggleState.Indeterminate;
            }
        }
        return base.ConvertTo(context, culture, value, destinationType);
    }

    public override bool CanConvertFrom(ITypeDescriptorContext context, Type sourceType)
    {
        return sourceType == typeof(ToggleState);
    }

    public override object ConvertFrom(ITypeDescriptorContext context, CultureInfo culture, object value)
    {
        ToggleState state = (ToggleState)value;

        switch (state)
        {
            case ToggleState.On:
                return true;
            case ToggleState.Off:
                return false;
            case ToggleState.Indeterminate:
                return false;
        }

        return base.ConvertFrom(context, culture, value);
    }
}

The check boxes are squeezed when the expanded state of the child nodes is changed in NodeCheckedChanged event.

Possible workaround: use Begin-End update block 

To reproduce: use the following code:

public Form1()
{
    InitializeComponent();

    this.radTreeView1.MultiSelect = true;
    for (int i = 0; i < 3; i++)
    {
        RadTreeNode node = new RadTreeNode();
        node.Text = "Node." + i;
        for (int j = 0; j < 3; j++)
        {
            node.Nodes.Add(new RadTreeNode("Node." + i + "." + j));
        }
        this.radTreeView1.Nodes.Add(node);
    }
    this.radTreeView1.SelectedNodeChanged += radTreeView1_SelectedNodeChanged;
}

private void radTreeView1_SelectedNodeChanged(object sender, Telerik.WinControls.UI.RadTreeViewEventArgs e)
{
    Console.WriteLine(e.Node.Text + ">> Selected: " + e.Node.Selected);
}

1.Select a node
2.Press Ctrl and click over the selected node again in order to unselect it. The SelectedNodeChanged event will not fire.

Workaround:

public class MyRadTreeNode : RadTreeNode
{
    public MyRadTreeNode(string text) : base(text)
    {
    }
    
    private static readonly MethodInfo OnSelectedNodeChangedMethodInfo =
        typeof(RadTreeViewElement).GetMethod("OnSelectedNodeChanged",
            BindingFlags.NonPublic | BindingFlags.Instance, null,
            new Type[] { typeof(RadTreeNode), typeof(RadTreeViewAction) }, null);

    protected override void OnNotifyPropertyChanged(PropertyChangedEventArgs args)
    {
        base.OnNotifyPropertyChanged(args);

        if (args.PropertyName == "Selected" && TreeViewElement != null)
        {
            OnSelectedNodeChangedMethodInfo.Invoke(TreeViewElement, new object[] { this, RadTreeViewAction.ByMouse });
        }
    }
}

To reproduce:
- Bind to object-relational data
- Add node via the context menu.
- The DataBoundItem in the NodeAdding and NodeAdded events is null.

Workaround:
- Add the node in the code behind:
private void RadTreeView1_NodeAdding(object sender, RadTreeViewCancelEventArgs e)
{
    e.Cancel = true;
    RadTreeNode node = radTreeView1.SelectedNode;
    if (node.Level == 0)
    {
        data.Add(new MyParentClass() { Text = "test" });
    }

}

To reproduce:

public Form1()
{
    InitializeComponent();
    this.radTreeView1.LazyMode = true; 
    this.radTreeView1.NodesNeeded+=radTreeView1_NodesNeeded;
}

private void radTreeView1_NodesNeeded(object sender, Telerik.WinControls.UI.NodesNeededEventArgs e)
{
    
}

Workaround: set the AllowArbitraryItemHeight property to true.

To reproduce:
1) Create a Windows Forms project.
2) Add a RadTreeView control.
3) Set the KeyboardSearchEnabled property to true.
4) Run the application and click in the tree (just to make sure it has the focus).
5) Using the keyboard, press a letter key.
6) Minimize the application.

The same exception occurs if there are no selected nodes.

Workaround:
class MyTreeView : RadTreeView
{
    protected override RadTreeViewElement CreateTreeViewElement()
    {
        return new MyTreeViewElement();
    }
    public override string ThemeClassName
    {
        get
        {
            return typeof(RadTreeView).FullName;
        }

        set
        {
            base.ThemeClassName = value;
        }
    }
}
class MyTreeViewElement : RadTreeViewElement
{
    protected override Type ThemeEffectiveType
    {
        get
        {
            return typeof(RadTreeViewElement);
        }
    }
    protected override RadTreeNode GetFirstMatch(string searchCriteria, RadTreeNodeCollection nodes)
    {
        if(this.SelectedNode == null && this.Items == null)
        {
            return null;
        }
        return base.GetFirstMatch(searchCriteria, nodes);
    }
}

When you open the last node for edit programmatically, either an exception is thrown or the editor is not opened.

Steps to reproduce:

1. Drag a RadTreeView from Toolbox and drop it onto the form.
2. Set the size of RadTreeView at design time to Size(354, 248).
3. Add a RadButton.
4. Use the following code:
public Form1()
{
    InitializeComponent(); 
    radTreeView1.AllowEdit = true; 
    radTreeView1.Nodes.Add("Root");
    for (int i = 0; i < 20; i++)
    {
        radTreeView1.Nodes[0].Nodes.Add("Test" + i.ToString());
    }
}

private void radButton1_Click(object sender, EventArgs e)
{
    RadTreeNode node = new RadTreeNode("Demo" + radTreeView1.Nodes[0].Nodes.Count.ToString());
    radTreeView1.Nodes[0].Nodes.Add(node);
    node.BeginEdit();
}

5. Click the button.
6. Collapse the root node.
7. Click the button again.



Workaround:

        private void button1_Click(object sender, EventArgs e)
        {
            RadTreeNode node = new RadTreeNode("Demo" + radTreeView1.Nodes[0].Nodes.Count.ToString());
            radTreeView1.Nodes[0].Nodes.Add(node);
            this.radTreeView1.TreeViewElement.Update(RadTreeViewElement.UpdateActions.Reset);
            node.Parent.Expanded = true;
            ((MyTreeViewElement)this.radTreeView1.TreeViewElement).SuspendEndEdit = true;
            node.BeginEdit();
            ((MyTreeViewElement)this.radTreeView1.TreeViewElement).SuspendEndEdit = false;
        } 

    public class MyTreeView : RadTreeView
    {
        protected override RadTreeViewElement CreateTreeViewElement()
        {
            return new MyTreeViewElement();
        }

        public override string ThemeClassName
        {
            get
            {
                return typeof(RadTreeView).FullName;
            }
            set
            {
            }
        }
    }

    public class MyTreeViewElement : RadTreeViewElement
    {
        public bool SuspendEndEdit = false;

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

        protected override bool EndEditCore(bool commitChanges)
        {
            if (SuspendEndEdit)
            {
                return false;
            }

            return base.EndEditCore(commitChanges);
        }
    }

To reproduce: use the following code snippet and perform the illustrated steps on the attached gif file:

public Form1()
{
    InitializeComponent();

    for (int i = 0; i < 5; i++)
    {
        this.radTreeView1.Nodes.Add("Node" + i);
    }

    this.radTreeView1.NodeRemoving += radTreeView1_NodeRemoving;

    this.radTreeView1.AllowRemove = true;
    this.radTreeView1.AllowDefaultContextMenu = true;
}

private void radTreeView1_NodeRemoving(object sender, Telerik.WinControls.UI.RadTreeViewCancelEventArgs e)
{
    DialogResult result = RadMessageBox.Show(String.Format("Do you really want to remove the node '{0}'?", e.Node.Text),
        "Question", System.Windows.Forms.MessageBoxButtons.YesNo, RadMessageIcon.Question);

    if (result != System.Windows.Forms.DialogResult.Yes)
    {
        e.Cancel = true;
    }
}

To reproduce:

public BlankTreeView()
{
    InitializeComponent();
    RadContextMenu menu = new RadContextMenu();
    RadMenuItem addItem = new RadMenuItem("Add");
    addItem.Click += addItem_Click;
    menu.Items.Add(addItem);
    this.radTreeView1.RadContextMenu = menu;
    
    BindingList<ParentObject> items = new BindingList<ParentObject>();
    for (int i = 0; i < 3; i++)
    {
        BindingList<ChildObject> subItems = new BindingList<ChildObject>();
        for (int j = 0; j < 10; j++)
        {
            subItems.Add(new ChildObject(j,"SubNode" + i + "." + j));
        }

        items.Add(new ParentObject(i ,"Node" + i,subItems));
    }

    this.radTreeView1.DataSource = items;
    this.radTreeView1.DisplayMember = "Title\\Description";
    this.radTreeView1.ChildMember = "ParentObject\\Children";
}

private void addItem_Click(object sender, EventArgs e)
{
    if (this.radTreeView1.SelectedNode != null)
    {
        if (this.radTreeView1.SelectedNode.Level == 0)
        {
            Random rand = new Random(); 
            ParentObject dataItem = this.radTreeView1.SelectedNode.DataBoundItem as ParentObject;
            if (dataItem != null)
            {
                dataItem.Children.Add(new ChildObject(rand.Next(0, 100),"New Node"));
            } 
        }
    }
}

public class ParentObject: INotifyPropertyChanged
{
    public event PropertyChangedEventHandler PropertyChanged;

    protected virtual void OnPropertyChanged(string propertyName)
    {
        if (PropertyChanged != null)
        {
            PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
        }
    }
    
    private int id;
    private string title;
    private BindingList<ChildObject> children;

    public int ID
    {
        get
        {
            return this.id;
        }
        set
        {
            this.id = value;
            OnPropertyChanged("ID");
        }
    }

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

    public BindingList<ChildObject> Children
    {
        get
        {
            return this.children;
        }
        set
        {
            this.children = value;
            OnPropertyChanged("Children");
        }
    }

    public ParentObject(int iD, string title, BindingList<ChildObject> children)
    {
        this.ID = iD;
        this.Title = title;
        this.Children = children;
    }
}

public class ChildObject: INotifyPropertyChanged
{ 
    public event PropertyChangedEventHandler PropertyChanged;

    private int id;
    private string description;

    public int ID
    {
        get
        {
            return this.id;
        }
        set
        {
            this.id = value;
            OnPropertyChanged("ID");
        }
    }

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

    public ChildObject(int iD, string description)
    {
        this.id = iD;
        this.description = description;
    }

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

Workaround: reset the TreeViewElement after adding the record:

radTreeView1.TreeViewElement.Update(RadTreeViewElement.UpdateActions.Reset);

To reproduce:
- Add items to the tree view (scrollbar must appear)
- Add context menu item which adds a new node and puts it in edit mode.
- Add a new node with the context menu item, scroll to the bottom, add item again.
- Scroll up and add item one more time.

Workaround:
void treeView_EditorRequired(object sender, TreeNodeEditorRequiredEventArgs e)
{
    e.Editor = new TreeViewTextBoxEditor();
}