Windows 8 Notification Center Charms bar and WinRT ToastNotificationManager clearing sync

Answer the core question first

Clearing a toast from the Charms bar does not automatically update the originating app’s internal state. The toast is removed from the system notification store, but no completion callback is sent to the app. The only way for an app to know that a toast has disappeared is to query the notification store after the fact or to rely on the ToastDismissed event, which is only raised under specific conditions.

What the API actually reports

• Manual dismissal (via the Charms bar or the toast itself) – The ToastDismissed event is raised for toasts that the app created and that are still in the active notification collection. The event’s reason field will contain UserDismissed.
• Banner timeout (default 10 s) – The toast simply expires; the expiration time is stored in the notification’s metadata, but no ToastDismissed event is fired.

Contract consistency across Windows 8 and 8.1

Documentation diverges:

• Windows 8 docs state that the ToastDismissed event is not guaranteed when a toast is cleared from the Charms bar.
• Windows 8.1 docs claim the event will fire if the user removes the toast, but only for toasts still present in the active collection.

There is no cross‑version guarantee that clearing a toast in the UI synchronizes with the app’s internal state. Developers should design for eventual consistency and explicitly handle the two scenarios above.

Practical verification steps

1. Register a ToastDismissed event handler in your app:

   var notifier = Windows.UI.Notifications.ToastNotificationManager.createToastNotifier();
   notifier.addEventListener('dismissed', e => {
       console.log('Dismissed reason:', e.detail.reason);
   });

2. Issue a toast with a short expiration (e.g., 5 s):

   var toastXml = ToastNotificationManager.getTemplateContent(ToastTemplateType.ToastText01);
   var toast = new ToastNotification(toastXml);
   toast.expirationTime = new Date(Date.now() + 5000);
   notifier.show(toast);

3. While the toast is still visible, open the Charms bar and manually clear it. Check the console – the handler should fire with reason = UserDismissed.
4. Repeat the test without manual dismissal. After 5 s, no event should be logged because the timeout does not trigger ToastDismissed.
5. Run the same test on a Windows 8.1 VM to confirm the behavior is identical.

Key take‑aways

• There is no automatic state sync when a toast is cleared from the Charms bar.
• Only manual dismissals trigger ToastDismissed events; timeouts do not.
• Documentation is inconsistent; rely on the practical test pattern above.
• These rules apply when the app is running in the foreground; background or terminated apps may not receive the event.

Missing diagnostic detail

If your app is not running in the foreground, the ToastDismissed event may never fire. Knowing whether the app is foreground or background will affect how you design your notification‑state logic.