C#

<small>private void cardsTreeView_DragDrop( object sender, DragEventArgs e )
{
    nodePosition.X = e.X;
    nodePosition.Y = e.Y;
    nodePosition = cardsTreeView.PointToClient(nodePosition);

    TreeNode dropNode = cardsTreeView.GetNodeAt(nodePosition);

    if (dropNode != null && dropNode.Parent == this.nodeToDelete.Parent)
    {
        TreeNode dragNode = this.nodeToDelete;
        
        if (dropNode == dragNode)
            return;

        dropNode.Parent.Nodes.Remove(this.nodeToDelete);
        dropNode.Parent.Nodes.Insert(dropNode.Index + 1, dragNode);

        Cards.MoveCardTo(GetIndexString(dropNode), GetIndexString(nodeToDelete));
        Cards.ReOrderCards();

        if (cardsTreeView.Nodes.Count > 0)
            cardsTreeView.Nodes.Clear();

        cardsTreeView.BeginUpdate();

        // load all cards from XML document
        Cards.GetAllCards(ref cardsTreeView);

        cardsTreeView.EndUpdate();
        cardsTreeView.ExpandAll();
       
        cardsTreeView.EndUpdate();
        
        // Fails to show the selected node 
        cardsTreeView.SelectedNode = cardsTreeView.Nodes[dropNode.Index];
        cardsTreeView.SelectedNode.EnsureVisible();
    }
}

private void cardsTreeView_DragEnter( object sender, DragEventArgs e )
{
    if(e.Data.GetDataPresent(DataFormats.Text))
        e.Effect = DragDropEffects.Move;
    else
        e.Effect = DragDropEffects.None;
}

private void cardsTreeView_ItemDrag( object sender, ItemDragEventArgs e )
{
    nodeToDelete = (TreeNode) e.Item;
    string strItem = e.Item.ToString();
    DoDragDrop(strItem, DragDropEffects.Copy | DragDropEffects.Move);
}
</small>