private void Overlay_MouseMoved(object sender, MouseHookEventArgs e)
 {
     if (_moving && _selectedItem != null)
     {
         _selectedItem.MoveTo(e.MouseXPos - _relativeMousePos.X, e.MouseYPos - _relativeMousePos.Y);
     }
 }
 public void AddItem(OverlayItem item)
 {
     (this.Content as Canvas).Children.Add(item);
     item.MoveTo(item.XPos, item.YPos);
 }