public event SankeySelectedItemsChangedEventHandler SelectedItemsChanged

Public Event SelectedItemsChanged As SankeySelectedItemsChangedEventHandler

HashSet<ExportItem> selectedExportItems = new HashSet<ExportItem>();

private void sankeyDiagramControl1_SelectedItemsChanged(object sender, SankeySelectedItemsChangedEventArgs e){
    selectedExportItems.Clear();
    foreach (SankeyLink link in e.SelectedLinks) {
        selectedExportItems.Add((ExportItem)link.Tags[0]);
    }
}

//...

public class ExportItem {
    public string Exporter { get; set; }
    public string Importer { get; set; }
    public double Sum { get; set; }

    public ExportItem(string from, string to, double weight) {
        this.Exporter = from;
        this.Importer = to;
        this.Sum = weight;
    }
}

Private selectedExportItems As HashSet(Of ExportItem) = New HashSet(Of ExportItem)()

Private Sub sankeyDiagramControl1_SelectedItemsChanged(ByVal sender As Object, ByVal e As SankeySelectedItemsChangedEventArgs)
    selectedExportItems.Clear()

    For Each link As SankeyLink In e.SelectedLinks
        selectedExportItems.Add(CType(link.Tags(0), ExportItem))
    Next
End Sub

'...

Public Class ExportItem
    Public Property Exporter As String
    Public Property Importer As String
    Public Property Sum As Double

    Public Sub New(ByVal from As String, ByVal [to] As String, ByVal weight As Double)
        Exporter = from
        Importer = [to]
        Sum = weight
    End Sub
End Class

sankey.EmptySankeyText.Text = string.Empty;
sankey.SelectedItemsChanged += Sankey_SelectedItemsChanged;
toolTipController = new ToolTipController();

sankey.EmptySankeyText.Text = String.Empty
AddHandler sankey.SelectedItemsChanged, AddressOf Sankey_SelectedItemsChanged
toolTipController = New ToolTipController()