We've tried, both by editing an existing button and creating a new one, to add a field for the customer to supply a message to us.
We've one so using "step 3" and adding our own custom prompt. In our case, the purpose is to have the customer tell us names to sign books to. It looks easy but doesn't work.
When testing the button, this text entry field does not appear, nor does the text we supplied to describe the purpose.
