fix checkmark demo

samples/ControlCatalog/MainWindow.xaml

@@ -41,7 +41,7 @@
           <NativeMenu>
            <NativeMenuItem Header="Check Me (None)" 
                             Command="{Binding ToggleMenuItemCheckedCommand}"
-                            ToggleType="CheckBox"
+                            ToggleType="None"
                             IsChecked="{Binding IsMenuItemChecked}"  />
             <NativeMenuItem Header="Check Me (CheckBox)" 
                             Command="{Binding ToggleMenuItemCheckedCommand}"