public void HideBlockingPlaceholder()
 {
     _updateAppControl = null;
     if (_blockingPlaceholder != null)
     {
         _blockingPlaceholder.Content    = null;
         _blockingPlaceholder.Visibility = Visibility.Collapsed;
     }
 }
        public void ShowBlockingPlaceholder(System.Action callback)
        {
            var updateAppControl = new UpdateAppControl();

            updateAppControl.TapBottomMenu += (o, e) =>
            {
                callback.SafeInvoke();
            };

            _blockingPlaceholder.Content    = updateAppControl;
            _blockingPlaceholder.Visibility = Visibility.Visible;
        }