iTextSharp ColumnText drawing and height not correct - itext

Question

I'm trying to place text into a ColumnText object and calculate its exact height. I'm using iTextSharp 5.5.9
What I'm finding is that there appears to be some "padding" at the top of the ColumnText object and it causes the height calculation to be flawed and the text to be misplaced. I'm trying to understand exactly what's happening - here's my code:
var doc = new Document(PageSize.LETTER, DocumentRenderer.PageMarginSize, DocumentRenderer.PageMarginSize, DocumentRenderer.PageTopMarginSize, DocumentRenderer.PageMarginSize);
doc.SetPageSize(PageSize.LETTER.Rotate());
var writer = PdfWriter.GetInstance(doc, fs);
doc.Open();
var x = 5;
var y = doc.PageSize.Height - 5;
var width = doc.PageSize.Width/ 2;
var height = doc.PageSize.Height - 10;
var lines = new List<string> { "Test string", };// "Test string 2", "Test string 3", "Test string 4" };
for (int i = 0; i < 6; i++)
{
lines.Add("Test String " + i);
}
lines.Add(lines.Aggregate((a, b) => a + ", " + b));
lines.Add(lines.Aggregate((a, b) => a + "\n" + b));
PdfContentByte cb = writer.DirectContent;
cb.SetTextRenderingMode(PdfContentByte.TEXT_RENDER_MODE_FILL);
cb.SetCMYKColorFill(DocumentRenderer.DarkColor.C, DocumentRenderer.DarkColor.M, DocumentRenderer.DarkColor.Y, DocumentRenderer.DarkColor.K);
Font ListFont = new Font(DocumentRenderer.TextFont, 12);
ColumnText ct = new ColumnText(cb);
ct.Leading = 14;
//ct.UseAscender = true;
ct.Alignment = Element.ALIGN_LEFT;
ct.SetSimpleColumn(x, y - height, x + width, y);
lines.ForEach(line =>
{
ct.AddText(new Phrase(line + "\n", ListFont));
});
ct.Go();
var height1 = (ct.LinesWritten * ct.Leading);
var height2 = y - ct.YLine;
DocumentRenderer.DrawBox(ref doc, ref writer, new BoxInfo(x, y, width, height2), DocumentRenderer.HighlightColor);
if (doc.IsOpen())
doc.Close();
Here are the results - please note that I highlighted the text with my cursor for effect.
I stumbled into this post (iText placement of Phrase within ColumnText) regarding UseAscender and tried it out by uncommenting that line in the code. You can see that on the right in the picture and it didn't appear to work like I was hoping.
What I really want is the text to still have its leading drawn correctly but for that to start at the top of the ColumnText. Also, I'm trying to get an accurate height for the text. The ct.YLine appears to give me the line at the bottom of the text but the text will overhang below that slightly. I'm not sure why that's not correct but I need to know the exact height if that's possible...
Anyone know how I might achieve these two things?