Public ReadOnly Property ResizingColumn As Integer

Dim instance As HeaderHitTestInformation
Dim value As Integer
 
value = instance.ResizingColumn

public int ResizingColumn {get;}

private void fpSpread1MouseUpClick(object sender, MouseEventArgs e)
{
      FarPoint.Win.Spread.HitTestInformation hti;
      FarPoint.Win.Spread.HeaderHitTestInformation hi;
      hti = fpSpread1.HitTest(e.X, e.Y);
      hi = hti.HeaderInfo;
      if (hti.Type == HitTestType.ColumnHeader)
      {
            MessageBox.Show(hi.ResizingColumn.ToString());
      }   
}

Private Sub FpSpread1MouseUp(ByVal sender As Object, ByVal e As MouseEventArgs)
      Dim hti As FarPoint.Win.Spread.HitTestInformation
      Dim hi As New FarPoint.Win.Spread.HeaderHitTestInformation
      hti = FpSpread1.HitTest(e.X, e.Y)
      hi = hti.HeaderInfo
      If hti.Type = HitTestType.ColumnHeader Then
            MessageBox.Show(hi.ResizingColumn)
      End If
End Sub