Hi Mike,
I have now been able to review your sample. I did have to do some changes to web.config, because of versioning issues for System.Web.Extensions. I don't remember the reason for every change I made, but most of them is related to version reference conflicts that only came to light when I added another wrapped control into the sample. I felt I needed to add that control, as we have been working on it before to test the wrapper. Nothing of these changes did affect how you did things. I think you did everything as you should have. I only write it here if you later want to review the changes I made, so you can possibly include them in some future project where you do have these conflicts I had.
The results of my were not to my liking. I had already tested the FreeTextBox control on a codebase after 6.4.0Beta1c was out and it was working. It is obvious that something has changed, so I opened a new issue on the subject which you can track here.
Thanks for the application,
Palli