[mobileweb] BackKeyPress

I develop an application with one window and add/remove views on purpose. Problem is with windows phone I cannot figure how to cancel the back button event in order to display my previous view? Event handler:

var appPage = tiwp8.getPhoneApplicationPage();
appPage.addEventListener('BackKeyPress', showPrevWnd);

In the callback function showPrevWnd(e) there is paramater "e.eventArgs":{"_hnd":0} How to get the associated System.ComponentModel.CancelEventArgs Object? which I want to put Cancel = true;?