public Flyout()
{
this.DefaultStyleKey = typeof(Flyout);
Window.Current.Activated += OnCurrentWindowActivated;
// set the default placement
this.Placement = PlacementMode.Top;
_windowBounds = Window.Current.Bounds;
_rootVisual = Window.Current.Content;
this.Loaded += OnLoaded;
_hostPopup = new Popup { IsHitTestVisible = false, Opacity = 0 };
_hostPopup.Closed += OnHostPopupClosed;
_hostPopup.Opened += OnHostPopupOpened;
_hostPopup.IsLightDismissEnabled = true;
_hostPopup.Child = this;
}