... in App. xaml.cs, as shown in Figure 4–4. Notice that, in App. xaml.cs, you will find various Windows Phone application-related events, such as Application_Launching, Application_Activated, Application_Deactivated, ... ApplicationCurrentMemoryUsage, and ApplicationPeakMemoryUsage. When you try to write out the DeviceName using string.Format the application throws a FormatException error because string.Format is ... that you will be required to use the Back button for going backward in your application, because having a separate Back button in the application might confuse the user. You will learn more about...