void OnDialogPageCompleted(object sender, ReturnData args) {
            // Set background from returned color
            contentGrid.Background = new SolidColorBrush(args.ReturnColor);

            // Set RadioButton for returned color
            foreach (UIElement child in radioStack.Children)
                if ((Color)(child as RadioButton).Tag == args.ReturnColor)
                    (child as RadioButton).IsChecked = true;

            (sender as DialogPage).Completed -= OnDialogPageCompleted;
        }
        protected override void OnNavigatedFrom(NavigationEventArgs e) {
            if (Completed != null) {
                // Create ReturnData object
                ReturnData returnData = new ReturnData();

                // Set the ReturnColor property from the RadioButton controls
                foreach (UIElement child in radioStack.Children)
                    if ((child as RadioButton).IsChecked.Value)
                        returnData.ReturnColor = (Color)(child as RadioButton).Tag;

                // Fire the Completed event
                Completed(this, returnData);
            }
            base.OnNavigatedFrom(e);
        }