The problem may be reproduced in example application in TreeView/First Look 
The scenario is as follows:
-enter some text as a filter
-delete text - filter should be off
-add new node by context menu -> "New Node" appears twice in the tree view

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 

When using TriStateMode with AutoCheckChildNodes, there is no way to determine whether the events are raised by a user action or by programatically checking a node.
view: CheckedMode enumeration for details

The checked state of parent node is incorrect when TriStateMode is enabled and it has a child node with no check type.

To reproduce:
  public Form1()
        {
            InitializeComponent();

            for (int i = 0; i < 10; i++)
            {
                RadTreeNode node = new RadTreeNode("Root node " + i);
                for (int j = 0; j < 10; j++)
         

Hide the AutoScroll property of RadTreeView in design time

FIX. RadTreeView - SelectedNode and SelectedNodes should be cleared when the DataSource of the control is set to null
test app:
using System;
using System.Data;
using System.Windows.Forms;
using Telerik.WinControls.UI;
namespace Lab.Tree
{
public partial class TreeResetSelectionAfterDataSourceIsSetToNull : MainForm
{
private RadTreeView treeView = new RadTreeView();
public TreeResetSelectionAfterDataSourceIsSetToNull()
{
InitializeComponent();
treeView.Dock = DockStyle.Fill;
treeView.Parent = this;
treeView.BringToFront();
DataTable table = new DataTable();
table.Columns.Add("Id");
table.Columns.Add("Name");
table.Rows.Add("1", "name1");
table.Rows.Add("2", "name2");
table.Rows.Add("3", "name3");
treeView.DisplayMember = "Name";
treeView.DataSource = table;
treeView.MultiSelect = true;
}
protected override void OnButton1Click()
{
Console.WriteLine(treeView.SelectedNodes.Count);
Console.WriteLine(treeView.SelectedNode);
treeView.DataSource = null;
Console.WriteLine("-------------------------------------------");
Console.WriteLine(treeView.SelectedNodes.Count);
Console.WriteLine(treeView.SelectedNode);
}
}
}

Checked state of the disabled nodes's check boxes is changed after scrolling.

Sort the selected nodes according to their position in the tree

ADD. RadTreeView - add support for binding the checkboxes of the nodes to a field in the data

The child nodes are aligned to the root nodes when ShowRootLines property is set to false.

ADD. RadTreeView - add NodeRemoving event

FIX. RadTreeView - the text of disabled nodes is not aligned correctly

I have implemented filtering in radtreeview by using following code in filter button click event:

rtvTaxReturnLines.filter=textFilter.text;

Note: here rtvTaxReturnLines is radtreeview name.

It filter the result by text given by user in textbox.But after filtering if we want to drag and drop some filter results from the treeview to gridview or within the treeview then it is not allowing dragdrop service in filtered result.

So is there an event triggered for added nodes when using a datasource?  I want to set the checked state based on a property on the databound item.  Basically this:

I have a treeview set like this in Q1 2012:
            treeViewProjets.DataSource = ViewModel.Projets;
            treeViewProjets.DisplayMember = @"Nom\Nom";
            treeViewProjets.ValueMember = @"Id\Id";
            treeViewProjets.ChildMember = @"Projets\ObjetsProjet";
            treeViewProjets.NodeAdded += new RadTreeView.RadTreeViewEventHandler(treeViewProjets_NodeAdded);
            treeViewProjets.NodeAdding += new RadTreeView.RadTreeViewCancelEventHandler(treeViewProjets_NodeAdding);
            treeViewProjets.NodeFormatting += new TreeNodeFormattingEventHandler(treeViewProjets_NodeFormatting);

I get a root node and many child nodes created, but the events NodeAdded and NodeAdding are never triggered, NodeFormatting triggers fine.

ADD. RadTreeView - when pressing a letter from the keyboard, the node starting with this letter should be selected.

Resolution: 
Added two new properties: KeyboardSearchEnabled and KeyboardSearchResetInterval. When set the KeyboardSearchEnabled property to true, user can navigate to an item by typing when RadTreeView is focused. 
You can set how long the user must wait before searching with the keyboard is reset using the KeyboardSearchResetInterval property. 

1. navigate to some tree item, try to right-click it to see context menu. It is working ok
2. have the focus on tree item, and having the mouse over that item, try to press context keyboard button

1. Have some tree with nodes and subnodes. Expand some of the nodes one by one until vertical scrollbar appears.
At the same time, there should be more nodes which have subnodes left
2. Do "Expand all" on some other node which is not expanded yet. Code used: "node.ExpandAll()"
Scroll bar reflect the area change and you can scroll up and down, it's ok
3. Do "Collapse all" on same node. Code used: "node.Collapse()"

Cut, Copy and Paste menu items in default context menu of RadTreeView are not localizable.

The context menu does not open at the right position when context menu button is used.