Public ReadOnly Property ViewportIndex As Integer

Dim instance As ColumnViewportWidthChangedEventArgs
Dim value As Integer
 
value = instance.ViewportIndex

public int ViewportIndex {get;}

private void fpSpread1_ColumnViewportWidthChanged(object sender, FarPoint.Win.Spread.ColumnViewportWidthChangedEventArgs e)
{
    if(e.ViewportIndex == 0)
    {
        MessageBox.Show("The new width is " + e.ViewportWidth);
        e.View.AddViewport(1, 1);
    }
}

Private Sub FpSpread1_ColumnViewportWidthChanged(ByVal sender As Object, ByVal e As FarPoint.Win.Spread.ColumnViewportWidthChangedEventArgs)
Handles FpSpread1.ColumnViewportWidthChanged
    If e.ViewportIndex = 0 Then
        MessageBox.Show("The new width is " & e.ViewportWidth)
        e.View.AddViewport(1, 1)
    End If
End Sub