I tend to organise my boards into frames (usually A4 frames) so that they are easy to use as slideshows or print to PDF for wider distribution after a design or planning session. In the map in the bottom right there is a blue box for every element within a frame but it it isn’t easy to see the boundaries of individual frames. If the frame boundaries were highlighted in some way e.g. a red border I would find that really helpful.
BTW. The more I use the tool the more delighted I am with it. It’s a pleasure to use. Thanks a million !