Public Class MachiningTreeExpanderView

   ' Evento necessario per impedire che venga creata la lavorazione quando si fa doppio click sulla ScrollBar
   Private Sub MachiningsTreeView_MouseDoubleClick(sender As Object, e As System.Windows.Input.MouseButtonEventArgs) Handles MachiningsTreeView.MouseDoubleClick
      Dim src As DependencyObject = VisualTreeHelper.GetParent(DirectCast(e.OriginalSource, DependencyObject))

      ' Your logic here
      If TypeOf src Is Control AndAlso src.[GetType]() <> GetType(Grid) Then
         e.Handled = True
      End If
   End Sub

End Class