protected override void OnBindingContextChanged()
        {
            base.OnBindingContextChanged();
            ISupportsStartFinish startFinish = this;

            startFinish.Start();
        }
        void DetachChild(object child)
        {
            ISupportsStartFinish startFinish = child as ISupportsStartFinish;

            if (startFinish != null)
            {
                startFinish.Finish();
            }
        }