Screens and non-navigational transitions
For transient UI, such as the login screen, you can use the Popup control to display content that partially covers the screen without implementing separate screens that would require full navigation. You can add the BackKeyPress event to your code and set e.Cancel to true while the pop-up window is visible to enable users to use the Back button to close the dialog box.
Multiple content views
For pages that display multiple sections of content, you can transition between different pieces of content without using navigation by simply rebinding the controls on your page to a new DataContext. Also, you can rebind by loading multiple instances of a UserControl inside the page, or using any other mechanism to display new content. You can choose how the user transitions forward and backward through the items. For instance, you can consider using the Previous and Next App bar buttons. However, we recommend that you avoid overusing the Back button for local transitions.
Saving state and tombstoning
You can save a local history of transitions that occur in a given page, so if an app is tombstoned, users can retrace their steps. For simple scenarios like previous or next browsing, all you need to do is save the page state in the current index. Doing this along with the use of the NavigationContext API should provide all the info you need to traverse the dataset when returning from a tombstoned state. For apps that have a more complex local transition history, such as free-form browsing of linked items, you may choose to store some of that history in page state, but you should put a reasonable limit on the items that you store. A key point is for the user to use the hardware Back button and return to the previous page instead of the previously viewed item.
The following table provides info about the common parts of an app that are considered to be pages.