private static void SetSlideFooter(PPT.Slide slide, int slideNumber)
        {
            // Insert the textboxes
            var textShape1 = PptShapeManager.AddTextBoxToSlide(
                slide,
                MsoTextOrientation.msoTextOrientationHorizontal,
                905f,
                512f,
                100f,
                40f);

            // Set the text in the textboxes
            PptShapeManager.SetTextBoxText(textShape1, "slide " + slideNumber);
            textShape1.TextEffect.FontBold = MsoTriState.msoFalse;
            textShape1.TextEffect.FontSize = 14f;
        }