To prevent ListPicker from raising BackKeyPress on your views. Otherwise, navigating back from a listpicker full screen mode will raise the key back event as if the page had actually gone back. This is probably true for any other controls that open something to fill the screen (LongListSelector, etc)

ListPickerHack.cs

RootFrame.BackKeyPress += (o, args) =>
  		{
				if (o is PhoneApplicationFrame)
				{
					var j = o as PhoneApplicationFrame;
					var listPicker = "/Microsoft.Phone.Controls.Toolkit;component/ListPicker/ListPickerPage.xaml";
					if (j.Source.OriginalString == listPicker)
					{
						return;
					}
				}

				WizardManager.Instance.Decrement();
				Debug.WriteLine("Notifying WizardManager of BackEvent");
			};