Is there a way to disable/restrict the Text Box Annotation type in the LF Client?  

Our workflow design writes an approval Text Box after each of our key approval steps.  The approval text box captures the approver's userid and places it in the text such as "Approved by <AD Domain>\John Doe".   We initially designed it with stamps but moved away from stamps because of the need to maintain a public stamp for each approver and the concerns with that.  Our concern with the Text Box is the potential to replicate the approval text box (same font size, border, etc) by an end user.  We do have requirements and other valid uses of other Public Stamps for the end users so we are not looking to disable all annotations.  We are looking for a method to allow them to add stamps, sticky notes, but not text boxes.