Within your project you can set up any number of "screen maps". The purpose of a "screen map" is to arrange pages in some visual way so that you can more easily navigate to the page that you are interested in.
You may drag/drop existing pages from the project tree on the left into the map area. - And you may create new pages by right-clicking into the map and selecting the "New layout..." popup menu item.
The maps are stored as XML file within your project directory - there in the ".cc/maps" folder.