Grrrr...this little quirk has wasted an hour of my life.
In Reader 7.0 and the preview option of Designer 7.0 you cannot click on a Read Only field.
In Reader 8.0 you can but you can't add text. This has meant that when testing to see whether a field was read only by trying to click into it it gave the appearance of being an edit field!
Beware or at least ensure that if you test this type of thing you do so by trying to type in the field as well!
My concern is that users will see a blinking cursor in a read only field and assume that this means that they should be able to enter content. Is this a bug or a 'design feature'?!