    private void convertToPdfButton_Click(object sender, EventArgs e)
    {
        // Create the PDF document where to add the HTML documents
        Document pdfDocument = new Document();

        // Set license key received after purchase to use the converter in licensed mode
        // Leave it not set to use the converter in demo mode
        pdfDocument.LicenseKey = "4W9+bn19bn5ue2B+bn1/YH98YHd3d3c=";

        // Create a PDF page where to add the first HTML
        PdfPage firstPdfPage = pdfDocument.AddPage();

        // Enable the creation of a table of contents from H1 to H6 tags found in HTML
        pdfDocument.TableOfContents.AutoTocItemsEnabled = autoTableOfContentsCheckBox.Checked;

        // Optionally set the table of contents title
        pdfDocument.TableOfContents.Title = "Table of Contents";

        // Optionally set the title style using CSS sttributes
        pdfDocument.TableOfContents.TitleStyle = "color:navy; font-family:'Times New Roman'; font-size:28px; font-weight:normal";

        // Optionally set the style of level 1 items in table of contents
        string level1TextStyle = "color:black; font-family:'Times New Roman'; font-size:20px; font-weight:normal; font-style:normal; background-color:#F0F0F0";
        pdfDocument.TableOfContents.SetItemStyle(1, level1TextStyle);

        // Optionally set the page numbers style of level 1 items in table of contents
        string level1PageNumberStyle = "color:black; padding-right:3px; background-color:#F0F0F0; font-size:14px; font-weight:bold";
        pdfDocument.TableOfContents.SetPageNumberStyle(1, level1PageNumberStyle);

        Cursor = Cursors.WaitCursor;
        string outPdfFile = @"DemoAppFiles\Output\HTML_to_PDF\Merge_Table_of_Contents.pdf";
        try
        {
            // Create the first HTML to PDF element
            HtmlToPdfElement firstHtml = new HtmlToPdfElement(0, 0, firstUrlTextBox.Text);

            // Optionally set a delay before conversion to allow asynchonous scripts to finish
            firstHtml.ConversionDelay = 2;

            // Enable or disable the table of contents for the first HTML document
            firstHtml.TableOfContentsEnabled = includeFirstHtmlTocCheckBox.Checked;

            // Add the first HTML to PDF document
            AddElementResult firstAddResult = firstPdfPage.AddElement(firstHtml);

            PdfPage secondPdfPage = null;
            PointF secondHtmlLocation = Point.Empty;

            if (startNewPageCheckBox.Checked)
            {
                // Create a PDF page where to add the second HTML
                secondPdfPage = pdfDocument.AddPage();
                secondHtmlLocation = PointF.Empty;
            }
            else
            {
                // Add the second HTML on the PDF page where the first HTML ended
                secondPdfPage = firstAddResult.EndPdfPage;
                secondHtmlLocation = new PointF(firstAddResult.EndPageBounds.Left, firstAddResult.EndPageBounds.Bottom);
            }

            // Create the second HTML to PDF element
            HtmlToPdfElement secondHtml = new HtmlToPdfElement(secondHtmlLocation.X, secondHtmlLocation.Y, secondUrlTextBox.Text);

            // Optionally set a delay before conversion to allow asynchonous scripts to finish
            secondHtml.ConversionDelay = 2;

            // Enable or disable the table of contents for the second HTML document
            secondHtml.TableOfContentsEnabled = includeSecondHtmlTocCheckBox.Checked;

            // Add the second HTML to PDF document
            secondPdfPage.AddElement(secondHtml);

            // Save the PDF document in a memory buffer
            byte[] outPdfBuffer = pdfDocument.Save();

            // Write the memory buffer in a PDF file
            System.IO.File.WriteAllBytes(outPdfFile, outPdfBuffer);
        }
        catch (Exception ex)
        {
            // The HTML to PDF conversion failed
            MessageBox.Show(String.Format("HTML to PDF Error. {0}", ex.Message));
            return;
        }
        finally
        {
            // Close the PDF document
            pdfDocument.Close();

            Cursor = Cursors.Arrow;
        }

        // Open the created PDF document in default PDF viewer
        try
        {
            System.Diagnostics.Process.Start(outPdfFile);
        }
        catch (Exception ex)
        {
            MessageBox.Show(String.Format("Cannot open created PDF file '{0}'. {1}", outPdfFile, ex.Message));
        }
    }