Some navigation categories such as folders can have a lot of options. Currently how photostructure works is to have the category and then have a group of random photos (which is nice), however sometimes it is nice to have just a list view without the photos shown to be able to drill down to a specific category quickly. For example if I have many folders like 30 or 40 folders and I want to view a specific folder it can take a while to scroll down to the specific folder and I don’t really care about the other photos.
That said I don’t have any suggestions on a ui element to swap between the different views, just that it might be a nice feature to have for navigation.