I know this might be too much to ask, but I’m very excited about the possibility of actually designing a cover page within Dorico, and I was just trying to put a border under a text frame in engrave mode. Unfortunately, Dorico only allows borders around the entire frame, so I was hoping that maybe a future version might add in the possibility to specify which side, like in Office products. (For the time being, I have worked around this by inserting an image.)
Thanks for the suggestion, clowergen. Another possibility you can use for now and which might be acceptable is to use another text frame that has its border switched on and zero height, so the border appears as a single line.