Missing characters in GuiMLTextControl?

I thought that I was missing something in my code, because the strings I were displaying always seemed to be missing a character (or two?) at the end of a line. I was concerned, but then I noticed that the GUI editor Help and the Common ChatGUI had the same problem!

Is this happening for anyone else? I'm wondering if it is another symptom of weirdness like my layer ordering issue.

As always, thanks for all the help.