I don't know whether this is a bug or a new idea, but in my opinion, it would be a good idea to make a change to this characteristic.
I have found that if you have the attribute checked for "Delineate Fields on Current Record Only" and you execute a PRINT command, the field boundaries do not print, no matter what you do with the color or line widths. If you uncheck "Delineate Fields on Current Record Only" then the field boundaries print.
Maybe I am mistaken or cannot think of a reason for the new Delineate Fields option to have anything to do with printing. I understand it to be a way to differentiate the active record from all others when viewing records in LIST VIEW.
In my layout, there is no list view. I am printing a letter-size form on a single page, using the Minimalist theme in FileMaker 14.