To reproduce:

protected override void OnLoad(EventArgs e)
{
    base.OnLoad(e);


    radTreeView1 = new RadTreeView();
    radTreeView1.Parent = this;


    for (int i = 0; i < 5; i++)
    {
        RadTreeNode n1 = new RadTreeNode("Node" + i);
        this.radTreeView1.Nodes.Add(n1);
        if (i % 2 == 0)
        {
            for (int j = 0; j < 2; j++)
            {
                RadTreeNode n2 = new RadTreeNode("Node" + i + "." + j);
                n1.Nodes.Add(n2);


                if (j % 2 == 0)
                {
                    for (int k = 0; k < 2; k++)
                    {
                        RadTreeNode n3 = new RadTreeNode("Node" + i + "." + j + "." + k);
                        n2.Nodes.Add(n3);
                    }
                }
            }
        }
    }
    radTreeView1.ShowRootLines = true;
    radTreeView1.ShowExpandCollapse = false;
    radTreeView1.ShowLines = true;
}


WORKAROUND: 
        void radTreeView1_NodeFormatting(object sender, TreeNodeFormattingEventArgs e)
        {
            if (radTreeView1.ShowExpandCollapse == false && radTreeView1.ShowRootLines == true)
            {
                if (e.Node.Parent == null && e.Node.Nodes.Count >0)
                {
                    TreeNodeLineElement lineElement = (TreeNodeLineElement)e.NodeElement.LinesContainerElement.Children[0];
                    lineElement.Visibility = ElementVisibility.Visible;
                    if (e.Node.Index==0)
                    {
                        lineElement.Type = TreeNodeLineElement.LinkType.RightTopAngleShape;
                    }
                    else if (e.Node.Index == radTreeView1.Nodes.Count -1)
                    {
                        lineElement.Type = TreeNodeLineElement.LinkType.RightBottomAngleShape;
                    }
                }
            }
        }

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

To reproduce:
-add RadTreeView and RadButton:
-use the following code:

public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();
        List<Distributor> distributors = new List<Distributor>()
        {
            new Distributor(432,"Distributor 1"),
            new Distributor(454,"Distributor 2"),
            new Distributor(438,"Distributor 3"),
            new Distributor(455,"Distributor 4")
        };

        List<Distributor> distributors2 = new List<Distributor>()
        {
            new Distributor(486,"Distributor 5"),
            new Distributor(487,"Distributor 6"),
            new Distributor(498,"Distributor 7"),
            new Distributor(475,"Distributor 8")
        };

        List<Product> products = new List<Product>();
        products.Add(new Product(567, "Bicycle", 5, distributors));
        products.Add(new Product(456, "Car", 5000,distributors2));
        products.Add(new Product(789, "Bike", 1500,null));

        BindingList<Category> categories = new BindingList<Category>();
        categories.Add(new Category("Bikes", products));
        categories.Add(new Category("Accessories", null));
        categories.Add(new Category("Clothing", null));

        radTreeView1.DataSource = categories;
        if ((radTreeView1.DataSource as BindingList<Category>).Count > 0)
        {
            radTreeView1.DisplayMember = "Name\\Description\\Name";
            radTreeView1.ChildMember = "Categories\\Products\\Distributors";   
        }
        
    }

    private void radButton1_Click(object sender, EventArgs e)
    {
        BindingList<Category> categories = radTreeView1.DataSource as BindingList<Category>;
        categories.Clear();
    }
}

public class Distributor
{
    private int _id;
    private string _name;

    public Distributor(int id, string name)
        {
            this._id = id;
            this._name = name;
        }

    public int Id
        {
            get
            {
                return this._id;
            }
            set
            {
                this._id = value;
            }
        }

    public string Name
        {
            get
            {
                return this._name;
            }
            set
            {
                this._name = value;
            }
        }
}

public class Product
{
    private int _id;
    private string _description;
    private float _price;
    private List<Distributor> _distributors;

    public List<Distributor> Distributors
        {
            get
            {
                return this._distributors;
            }
            set
            {
                this._distributors = value;
            }
        }

    public int ID
        {
            get
            {
                return _id;
            }
            set
            {
                _id = value;
            }
        }

    public string Description
        {
            get
            {
                return _description;
            }
            set
            {
                _description = value;
            }
        }

    public float Price
        {
            get
            {
                return _price;
            }
            set
            {
                _price = value;
            }
        }

    public Product(int id, string description, float price, List<Distributor> distributors)
    {
        _id = id;
        _description = description;
        _price = price;
        _distributors = distributors;
    }
}

public class Category
{
    public Category(string name, List<Product> products)
    {
        _name = name;
        _products = products;
    }

    private List<Product> _products;
    private string _name;

    public string Name
        {
            get
            {
                return _name;
            }
            set
            {
                _name = value;
            }
        }

    public List<Product> Products
        {
            get
            {
                return _products;
            }
            set
            {
                _products = value;
            }
        }
}

When you click the button, ArgumentOutOfRangeException is thrown.

Workaround: instead of clearing the BindingList, remove each list item one by one:
while (categories.Count>0)
{
    categories.RemoveAt(0);
}

Workaround:
Instead of {RadTreeNode}.Nodes.Clear(), use 

 while ({RadTreeNode}.Nodes.Count>0)
          {
              {RadTreeNode}.Nodes.RemoveAt(0);
          }

To reproduce:
- Add a RadTreeView which have parent and child nodes to a form.
- Expand nodes until the both scrollbars are simultaneously shown.
- You will notice that you cannot scroll to the last item.

Workaround:
- Subscribe to the following ScrollerUpdated event handler:

void Scroller_ScrollerUpdated(object sender, EventArgs e)
{
radTreeView1.TreeViewElement.InvalidateMeasure();

}

- You can subscribe to this event with the following line of code:
radTreeView1.TreeViewElement.Scroller.ScrollerUpdated += Scroller_ScrollerUpdated;

To reproduce: 
Add a RadTreeView to a form and use the following code:
private List<EntityA> entities = new List<EntityA>(); public Form1() { InitializeComponent(); radTreeView1.TriStateMode = true; entities = new List<EntityA>(); for (int i = 0; i < 10; i++) { var newEntityI = new EntityA(i.ToString()); for (int j = 0; j < 100; j++) { var newEntityJ = new EntityB(j.ToString()); for (int k = 0; k < 1000; k++) { var newEntityK = new EntityC(k.ToString()); newEntityJ.Entities.Add(newEntityK); } newEntityI.Entities.Add(newEntityJ); } entities.Add(newEntityI); } } private void checkBox1_CheckedChanged(object sender, EventArgs e) { foreach (var node in radTreeView1.Nodes) { node.Checked = checkBox1.Checked; } } private void radTreeView1_NodesNeeded(object sender, NodesNeededEventArgs e) { if (e.Parent == null) { foreach (var entity in entities) { e.Nodes.Add(new RadTreeNode(entity.Name, false) { CheckState = ToggleState.Off, Tag = entity }); } } else if (e.Parent.Tag is EntityA) { var currentEntity = e.Parent.Tag as EntityA; foreach (var entity in currentEntity.Entities) { e.Nodes.Add(new RadTreeNode(entity.Name, false) { CheckState = e.Parent.CheckState, Tag = entity }); } } else if (e.Parent.Tag is EntityB) { var currentEntity = e.Parent.Tag as EntityB; foreach (var entity in currentEntity.Entities) { e.Nodes.Add(new RadTreeNode(entity.Name, false) { CheckState = e.Parent.CheckState, Tag = entity }); } } else if (e.Parent.Tag is EntityC) { } } 
Put a breakpoint in the last If statement, you will notice that the breakpoint is being hit, while it is not if the TrieStateMode is set to false 

Workaround: 
Use the following custom RadTreeNode: 
public class MyTreeNode : RadTreeNode { private FieldInfo triStateField; public MyTreeNode() : base() { } public MyTreeNode(string text) : base(text) { } public MyTreeNode(string text, RadTreeNode[] children) : base(text, children) { } public MyTreeNode(string text, bool expanded) : base(text, expanded) { } public MyTreeNode(string text, Image image) : base(text, image) { } public MyTreeNode(string text, Image image, bool expanded) : base(text, image, expanded) { } public override ToggleState CheckState { get { return base.CheckState; } set { bool set = false; if (this.TreeViewElement != null && this.TreeViewElement.TriStateMode) { if (this.triStateField == null) { this.triStateField = typeof(RadTreeViewElement).GetField("triStateMode", BindingFlags.Instance | BindingFlags.NonPublic); } triStateField.SetValue(this.TreeViewElement, false); set = true; } base.CheckState = value; if (set) { this.triStateField.SetValue(this.TreeViewElement, true); } } } }

Add e.Action in SelectedNodeChanging similar to the one in the standard TreeView.BeforeSelect event which indicates what caused the event - mouse click, key pressed, or other

To reproduce: Add a RadTreeView with hierarchical data. Select a node with hierarchy level > 0. Call the Clear method of the Nodes collection. Refill the tree, drag and drop a node, you will see that two nodes will be dropped since the previous node's Selected property is set to true. 

Workaround: private void DetachAllNodes(RadTreeNode parent) { this.CleanNode(parent); foreach (RadTreeNode node in parent.Nodes) { this.DetachAllNodes(node); } } private void CleanNode(RadTreeNode node) { node.Current = false; node.Selected = false; } foreach (RadTreeNode node in tree.Nodes) { this.DetachAllNodes(node); } tree.Nodes.Clear();

Workaround:
this.radTreeView1.SelectedNode = null;

To reproduce: this issue is reproducible under Windows8 OS only
-add RadTreeView from the Toolbox to the Form and add several tree nodes at design time;
-add RadContextMenu from the Toolbox and add several items at design time;
Use the following code:
public Form1()
{
    InitializeComponent();

    this.radTreeView1.RadContextMenu = this.radContextMenu1;
}
-run the application;
-select a tree node;
-right mouse click over the node to show the context menu; As a result the main form looses focus and you are unable to click anywhere outside the RadTreeView.
This issue is inconstant and it is not appearing every time.

Workaround: use ContextMenu property instead:
public Form1()
{
    InitializeComponent();

    ContextMenu menu = new ContextMenu();

    foreach (var item in radContextMenu1.Items)
    {
        menu.MenuItems.Add(new MenuItem(item.Text));
    }

    this.radTreeView1.ContextMenu = menu;
    // this.radTreeView1.RadContextMenu = this.radContextMenu1;
}

To reproduce:
Add a RadTreeView with some nodes and you will notice that the font is different than other controls.

Workaround:
void tree_NodeFormatting(object sender, TreeNodeFormattingEventArgs e)
{
    e.NodeElement.ContentElement.TextRenderingHint = System.Drawing.Text.TextRenderingHint.SystemDefault;
}

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: - add a RadTreeView - enable multiselect - select at least 1 node - call radTreeView1.SelectedNodes.Clear() Workaround: Clear the nodes manually: foreach (var node in this.radTreeView1.SelectedNodes.ToList()) { node.Selected = false; }

To reproduce: private void btnFill_Click(object sender, EventArgs e) { radTreeView.BeginUpdate(); radTreeView.Nodes.Add(new RadTreeNode("root 1")); radTreeView.Nodes.Add(new RadTreeNode("root 2")); radTreeView.Nodes.Add(new RadTreeNode("root 3")); radTreeView.Nodes.Add(new RadTreeNode("root 4")); radTreeView.Nodes[radTreeView.Nodes.Count - 1].Expand(); for (int i = 0; i < 30; i++) { radTreeView.Nodes[radTreeView.Nodes.Count - 1].Nodes.Add(new RadTreeNode("text" +i)); } radTreeView.EndUpdate(); } private void radButton1_Click(object sender, EventArgs e) { radTreeView.BeginUpdate(); foreach (var node in radTreeView.Nodes[radTreeView.Nodes.Count - 1].Nodes.ToArray()) { node.Remove(); } for (int i = 0; i < 99; i++) { radTreeView.Nodes[radTreeView.Nodes.Count - 1].Nodes.Add(new RadTreeNode("aasdasd")); } radTreeView.EndUpdate(); } Workaround - reset the traverser and update the scroll value prior removing the nodes radTreeView.TreeViewElement.Scroller.Traverser.Reset(); 

this.treeView.TreeViewElement.Scroller.UpdateScrollValue();

TreeViewDragDropService cannot be canceled on the following event:

radTreeView1.TreeViewElement.DragDropService.PreviewDragOver

When a tree is bound using object-relational binding the editing does not work for nodes that are on level higher than the first.

To reproduce: Add some nodes to a tree, and then clear them and move them to another tree. The inner nodes expand/collapse does not work correctly: void radButton1_Click(object sender, EventArgs e) { tree1.Nodes.Clear(); tree2.Nodes.AddRange(nodes); } RadTreeView tree1 = new RadTreeView(); RadTreeView tree2 = new RadTreeView(); List<RadTreeNode> nodes = new List<RadTreeNode>(); private void Populate(RadTreeView tree) { RadTreeNode n11 = new RadTreeNode("11"); RadTreeNode n12 = new RadTreeNode("12"); RadTreeNode n13 = new RadTreeNode("13"); RadTreeNode n14 = new RadTreeNode("14"); nodes.Add(n11); nodes.Add(n12); nodes.Add(n13); nodes.Add(n14); RadTreeNode n21 = new RadTreeNode("21"); RadTreeNode n22 = new RadTreeNode("22"); RadTreeNode n23 = new RadTreeNode("23"); RadTreeNode n24 = new RadTreeNode("24"); n11.Nodes.Add(n21); n11.Nodes.Add(n22); n11.Nodes.Add(n23); n11.Nodes.Add(n24); RadTreeNode n31 = new RadTreeNode("31"); RadTreeNode n32 = new RadTreeNode("32"); RadTreeNode n33 = new RadTreeNode("33"); RadTreeNode n34 = new RadTreeNode("34"); n21.Nodes.Add(n31); n21.Nodes.Add(n32); n21.Nodes.Add(n33); n21.Nodes.Add(n34); tree.Nodes.AddRange(nodes); } 1. Run 2. Expand all nodes in tree1 3. Select node 23 4. Press button move right 5. Click at "plus" at node 21. -> expand collapse does not work correctly Workaround - instead of calling the Clear method of the Nodes collection, remove them manually: while (tree1.Nodes.Count > 0) { tree1.Nodes.RemoveAt(0); }

RadTreeView - Traverser throws exception if you clear and recreate all sub nodes of some node.  

Steps to reproduce:
1. Create RadTreeView with one node.
2. Add 100 sub nodes.
3. Clear the sub nodes.
4. Move scroll.

WorkAround:

    private void RefreshNodes()
    {
      
      radTreeView1.BeginUpdate();

      this.radTreeView1.TreeViewElement.Scroller.Traverser.Position = groupNode;
      this.radTreeView1.TreeViewElement.Scroller.Traverser.Reset();

      this.radTreeView1.SelectedNodes.Clear();
      groupNode.Nodes.Clear();
 
      AddNodes(groupNode.Nodes, 1, 100);

      groupNode.Expand();
      radTreeView1.EndUpdate();

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

If you have a node with a very long text that requires horizontal scrollbar and at the same time you have a many nodes which requires a vertical scrollbar in some border cases the long text of the node is cut off (with ellipsis).

Workaround:
RadTreeView1.TreeViewElement.TreeNodeProvider.Reset()