**[Question]**

On Windows Phone 8.1, what exactly happens in between the time when the user leaves the app and the OnSuspended event fires? I'm having trouble with the ability to manage objects in that span, in particular MediaCpture object.

To better explain the problem, here is the scenario: 

1. The user is on a page with a video preview being pumped to a CaptureElement
2. The user taps the Start button
3. The user taps Back button and returns to the page with a broken MediaCapture

With WinRT there isn't an **ObscuredEvent** and **OnNavigatingFrom** doesn’t fire unless you’re going to another page in the same Frame. After some investigation, I've found that the only event that fires is **Window.Current.VisibilityChanged**

I've gone ahead and hook it when the page is **NavigatedTo** and unhooked in **OnNavigatedFrom** (see ex2 below). Inside the event, I check for parameter that tells if the app is hiding or showing and dispose/initialize accordingly(see ex.1 below). 

**[Problem]**

However, this **only** works with the debugger attached. If I do this without the debugger attached, it doesn't reinitialize and ***frequently crashes the camera*** and I have to literally reboot the device.

Code Example 1 (note: e.Visible == false is leaving the app and true when returning)

```cs
async void Current_VisibilityChanged(object sender, VisibilityChangedEventArgs e)
{
     if (!e.Visible) //means leaving the app
     {
         await DisposeAll(); //cleans the MediaCapture and CaptureElement
     }
     else
     {
         if(mediaCaptureManager != null) await DisposeAll();

         await Initialization(); //set up camera again
     }
}

```

Example 2 (hooking into the event)

```cs
protected override void OnNavigatedTo(NavigationEventArgs e)
{
    Window.Current.VisibilityChanged += Current_VisibilityChanged;

    this.navigationHelper.OnNavigatedTo(e);
}

protected async override void OnNavigatedFrom(NavigationEventArgs e)
{
    Window.Current.VisibilityChanged -= Current_VisibilityChanged;

    this.navigationHelper.OnNavigatedFrom(e);
}

```

**[Update: Resolution]**

Instead of using VisibilityChanged, hook into Window.Current.Activated on the page's constructor. With the debugger completely detached, the Activated event will provide the WindowActivationState parameter in the WindowActivatedEventArgs. Like this:

```
private async void CurrentOnActivated(object sender, WindowActivatedEventArgs e)
{
    if(e.WindowActivationState == CoreWindowActivationState.Deactivated)
    {
        //dispose MediaCapture here
    }
    else if(e.WindowActivationState == CoreWindowActivationState.CodeActivated || e.WindowActivationState == CoreWindowActivationState.PointerActivated)
    {
        //initialize MediaCapture here
    }
}

```