Private Sub Button_StartStop_Click(ByVal sender As System.Object, ByVal e As _
   System.EventArgs) Handles Button_StartStop.Click
 
        If Me.PlanningGuideDataBindingSource.Position < 0 Then
            MsgBox("Keine Projektwahl") : Exit Sub
        End If
 
        'Aktuell ausgewähltes Projekt
        Dim row As DataRow = DirectCast(Me.PlanningGuideDataBindingSource( _
          Me.PlanningGuideDataBindingSource.Position), DataRowView).Row
        Dim projectid As Integer = CInt(row.Item("ID"))
        Dim rowindex As Integer = TimeTable_IndexOf(projectid)
 
        With timetable
            If rowindex = -1 Then
                'Keine offene Zeitmessung --> neue Messung starten
                .Rows.Add(.Rows.Count, projectid, Now, DBNull.Value, _
                  DBNull.Value)
            Else
                'vorhandene Zeitmessung abschließen
                .Rows(rowindex)("Ende") = Now
                Dim start As Date = DirectCast(.Rows(rowindex)("Start"), Date)
                Dim ende As Date = DirectCast(.Rows(rowindex)("Ende"), Date)
                .Rows(rowindex)("Intervall") = _
                    New TimeSpan(ende.Ticks - start.Ticks).TotalSeconds
                Hour_confirmation_quotationTextBox.Text = ende
            End If
        End With
        bsTime.ResetBindings(False)
 
        StartStopButtontext()
 
        elapsetimer.Start()
 
    End Sub

Private Sub elapsetimer_Tick(ByVal sender As Object, ByVal e As _
  System.EventArgs) Handles elapsetimer.Tick
 
        lblElapsed.Text = String.Empty
 
        With timetable
            For i As Integer = 0 To .Rows.Count - 1
                'Laufende Zeitmessung
                If IsDBNull(.Rows(i)("Ende")) Then
                    'Seit dem Start verstrichene Sekunden 
                    'in die Intervall-Spalte eintragen
                    Dim start As Date = DirectCast(.Rows(i)("Start"), Date)
                    Dim elapsed As New TimeSpan(Now.Ticks - start.Ticks)
 
                    .Rows(i)("Intervall") = elapsed.TotalSeconds
 
                    'Label für Anzeige der verstrichenen Zeit seit Start 
                    lblElapsed.Text = "Projekt-ID (" & .Rows(i)( _
                      "ProjectID").ToString & "): " & elapsed.ToString("g")
                    lblElapsed.Refresh()
                End If
            Next i
        End With
    End Sub