AjaxControlToolkit.Design.AccordionDesigner.GetDesignTimeHtml C# (CSharp) Method

        public override string GetDesignTimeHtml()
        {
            if(_accordion.Height == Unit.Empty)
                _accordion.Height = new Unit(175);

            if(_accordion.Width == Unit.Empty)
                _accordion.Width = new Unit(300);

            // Ensure the controls have been created
            var controls = _accordion.Controls;

            // Get the base html for the accordion's div
            // so that any accordion styles will be applied
            // Remove the closing div tag so we can insert the HTML
            // for all of the panes
            var originalHtml = base.GetDesignTimeHtml();

            var lastIdx = originalHtml.ToString().IndexOf("<div", 1);
            if(lastIdx > 0)
                originalHtml = originalHtml.ToString().Substring(0, (originalHtml.ToString().IndexOf("<div", 1)));
            else
                originalHtml = originalHtml.Remove(originalHtml.Length - 6, 6);

            // remove all tabs and new lines
            originalHtml = originalHtml
                    .Replace("\r", "")
                    .Replace("\n", "")
                    .Replace("\t", "");

            // apply overflow:scroll so user will able to see accordion contents in design time
            // when it's overflow style if it doesn't exists
            if(!originalHtml.Contains("overflow")) {
                originalHtml = originalHtml.Replace("style=\"", "style=\"overflow:scroll;");
            }

            var html = new StringBuilder(originalHtml);
            // Add the HTMl for each pane ---------------
            // Clone Panes to prevent direct access to _accordion.Panes so it will avoid
            //    "collection was modified enumeration operation may not execute" exception when user
            //    modify design in source view and back again to design view
            foreach(var pane in (AccordionPane[])_accordion.Panes.ToArray().Clone()) {
                html.Append("<span>");
                var headerCSS = !string.IsNullOrEmpty(pane.HeaderCssClass) ? pane.HeaderCssClass : _accordion.HeaderCssClass;
                html.AppendFormat("<div class=\"{0}\">", headerCSS);
                var builder = pane.Header as TemplateBuilder;
                if(builder != null)
                    html.Append(builder.Text);
                else {
                    html.Append("AccordionPane Header ");
                    html.Append(pane.ID);
                }
                html.Append("</div>");

                var contentCSS = !String.IsNullOrEmpty(pane.ContentCssClass) ? pane.ContentCssClass : _accordion.ContentCssClass;
                html.AppendFormat("<div class=\"{0}\">", contentCSS);
                builder = pane.Content as TemplateBuilder;
                if(builder != null)
                    html.Append(builder.Text);
                else {
                    html.Append("AccordionPane Content ");
                    html.Append(pane.ID);
                }

                html.Append("</div>");
                html.Append("</span>");
            }

            html.Append("</div>");
            return html.ToString();
        }