Private Sub TreeView1_NodeMouseClick(sender As System.Object, e As System.Windows.Forms.TreeNodeMouseClickEventArgs) Handles TreeView1.NodeMouseClick
  If e.Button = Windows.Forms.MouseButtons.Right Then
    Dim n As TreeNode = TreeView1.GetNodeAt(e.X, e.Y)
    'выделить элемент
    'If TreeView1.GetNodeAt(e.X, e.Y) IsNot Nothing Then
    '  TreeView1.SelectedNode = TreeView1.GetNodeAt(e.X, e.Y)
    'End If
  End If
End Sub