How to Remove FreeText Border When Using ImportAnnotationFromXfdf

I am using ImportAnnotationFromXfdf to create FreeText annotations.  This is working, but I always get a red border around the FreeText.  How can I remove the border entirely?  I've tried setting the width attribute to zero on the <freetext> tag, but I still get the border.

Also, where is the defaultappearance tag documented?  Thanks.