Hello,
This certainly does not seem right. The problem is that I am trying to reproduce this locally, unfortunately without much success. No matter what I tried (and I tried several different setups plus I followed your instructions), the result was always a working edit box for me.
Maybe the best approach in cases like that is to contact our developer support department directly - they can be reached from this page:
http://devcenter.infragistics.com/Protected/SubmitSupportIssue.aspx
If you have a small subset of your project reproducing the issue, it will be much easier for them to get the repro running and advise further.