Possible fix when inapp theme is changed

samples/NotificationFlyoutSample/Shell.xaml

@@ -7,6 +7,11 @@
         Width="330"
         Height="500"
         Margin="24">
+        <ComboBox x:Name="Theme" SelectionChanged="Theme_SelectionChanged">
+            <ComboBoxItem Content="Default" />
+            <ComboBoxItem Content="Dark" />
+            <ComboBoxItem Content="Light" />
+        </ComboBox>
         <Button Margin="0,0,0,8" Content="Button" />
         <Slider Margin="0,0,0,8" />
         <TextBox Margin="0,0,0,8" />

samples/NotificationFlyoutSample/Shell.xaml.cs

@@ -1,27 +1,26 @@
-using System;
-using System.Collections.Generic;
-using System.IO;
-using System.Linq;
-using System.Runtime.InteropServices.WindowsRuntime;
-using Windows.Foundation;
-using Windows.Foundation.Collections;
-using Windows.UI.Xaml;
-using Windows.UI.Xaml.Controls;
-using Windows.UI.Xaml.Controls.Primitives;
-using Windows.UI.Xaml.Data;
-using Windows.UI.Xaml.Input;
-using Windows.UI.Xaml.Media;
-using Windows.UI.Xaml.Navigation;
-
-// The User Control item template is documented at https://go.microsoft.com/fwlink/?LinkId=234236
-
-namespace NotificationFlyoutSample
+namespace NotificationFlyoutSample
 {
-    public sealed partial class Shell : UserControl
+    public sealed partial class Shell
     {
         public Shell()
         {
-            this.InitializeComponent();
+            InitializeComponent();
+        }
+
+        private void Theme_SelectionChanged(object sender, Windows.UI.Xaml.Controls.SelectionChangedEventArgs e)
+        {
+            switch (Theme.SelectedIndex)
+            {
+                case 0:
+                    RequestedTheme = Windows.UI.Xaml.ElementTheme.Default;
+                    break;
+                case 1:
+                    RequestedTheme = Windows.UI.Xaml.ElementTheme.Dark;
+                    break;
+                case 2:
+                    RequestedTheme = Windows.UI.Xaml.ElementTheme.Light;
+                    break;
+            }
         }
     }
 }