Enable Toasts from Within Applications
The Toast UI metaphor is useful for showing transient messages to the user such as authentication failures or other other messages that do not require the user's immediate attention.
In the current ShellTile API, a toast will not be displayed if the current foreground application is the caller of the ShellToast.Show method. It would be great if this was changed so that we could present in-app toasts. We can then user the NavigateUri property to navigate the user to a different part of the app if necessary.
Thank you for the suggestion. We are not adding this capability in the 8.0 release, but know that it is high on the consideration list for future Windows Phone releases.
Keep those suggestions and votes coming!
Have you tried the Coding4Fun Tools on Codeplex? They have a ToastPrompt notification for in-app toasts.