Update Samples

Author: ghost1372

dev/DevWinUI.Controls/Controls/WindowedContentDialog/Underlay/UnderlayMode.cs

@@ -1,6 +1,7 @@
 namespace DevWinUI;
 public enum UnderlayMode
 {
+    None,
     SmokeLayer,
     SystemBackdrop
 }

dev/DevWinUI.Gallery/Views/Pages/Common/MessageBoxPage.xaml

@@ -46,7 +46,7 @@
                         <ComboBox x:Name="CmbUnderlayMode"
                                   Header="Underlay Mode"
                                   ItemsSource="{x:Bind ViewModel.UnderlayModeItems, Mode=OneWay}"
-                                  SelectedIndex="0" />
+                                  SelectedIndex="1" />
                         <ComboBox x:Name="CmbUnderlayBackdrops"
                                   Header="Underlay Backdrop"
                                   ItemsSource="{x:Bind ViewModel.BackdropItems, Mode=OneWay}"

dev/DevWinUI.Gallery/Views/Pages/Common/WindowedContentDialogPage.xaml

@@ -46,7 +46,7 @@
                         <ComboBox x:Name="CmbUnderlayMode"
                                   Header="Underlay Mode"
                                   ItemsSource="{x:Bind ViewModel.UnderlayModeItems, Mode=OneWay}"
-                                  SelectedIndex="0" />
+                                  SelectedIndex="1" />
                         <ComboBox x:Name="CmbUnderlayBackdrops"
                                   Header="Underlay Backdrop"
                                   ItemsSource="{x:Bind ViewModel.BackdropItems, Mode=OneWay}"