Question

How do I stop my application from going back when the user clicks on the “Cancel” button after hitting the back button?

      protected override void OnBackKeyPress(System.ComponentModel.CancelEventArgs e)
    {
        var buttonInfo = MessageBox.Show("Are you sure you want to exit?", "Exit", MessageBoxButton.OKCancel);
        if (buttonInfo == MessageBoxResult.OK)
        {
            this.NavigationService.GoBack();
        }
        else
        {
            //How to stop page from navigating
        }
    }

Answer 1

Use CancelEventArgs to cancel the action, property Cancel.

protected override void OnBackKeyPress(System.ComponentModel.CancelEventArgs e)
{
    // If the event has already been cancelled, do nothing
    if(e.Cancel)
        return;

    var buttonInfo = MessageBox.Show("Are you sure you want to exit?", "Exit", MessageBoxButton.OKCancel);
    if (buttonInfo == MessageBoxResult.OK)
    {
        this.NavigationService.GoBack();
    }
    else
    {
        //Stop page from navigating
        e.Cancel = true;
    }
}