A general question regarding tombstoning WP7 applications. What do you think a users expectations are? And what level of tombstoning support are you providing in your application?
For example, if you have an application that navigates across multiple pages, would a user returning to your tombstoned application expect it to display the last page they viewed?
If so, what if the last page they viewed was a pivot? would they expect it to be at the same location / pivot-page?
Thanks.
Tombstoning can occur under a number of circumstances (including something as simple as answering a phone call) and so your application should appear to be in exactly the same state (or as close to it) as when the user last saw your application.
The operating system handles which page to load for you and the previous page back stack is retained (assuming that you are using standard page navigation within your application). If the page loaded on activation has a Pivot control in it, or other control that supports selection, then yes, the user's selection should be remembered on deactivation and restored on activation.
Charles Petzold's book Programming Windows Phone 7 has a section that covers this in chapter 6. Kevin Marshall has a good blog post that covers WP7 serialization; for the best performance you should use binary serialization.