Chinese language treatment for WinUI bug.

Wino.Mail.WinUI/Controls/Calendar/CalendarItemCommandBarFlyout.cs

@@ -60,7 +60,7 @@ public partial class CalendarItemCommandBarFlyout : CommandBarFlyout
 
         if (menuItem.HasChildren)
         {
-            var flyout = new MenuFlyout();
+            var flyout = new WinoMenuFlyout();
             PopulateMenuFlyoutItems(flyout.Items, menuItem.Children);
             button.Flyout = flyout;
         }

Wino.Mail.WinUI/Controls/MenuFlyoutLanguageHelper.cs

@@ -0,0 +1,23 @@
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.UI.Xaml.Controls;
+using Wino.Core.Domain.Enums;
+using Wino.Core.Domain.Interfaces;
+
+namespace Wino.Mail.WinUI.Controls;
+
+internal static class MenuFlyoutLanguageHelper
+{
+    private const string ChineseLanguageTag = "zh-CN";
+
+    public static void Apply(MenuFlyoutItemBase item)
+    {
+        if (WinoApplication.Current.Services.GetRequiredService<IPreferencesService>().CurrentLanguage == AppLanguage.Chinese)
+        {
+            item.Language = ChineseLanguageTag;
+        }
+        else
+        {
+            item.ClearValue(MenuFlyoutItemBase.LanguageProperty);
+        }
+    }
+}

Wino.Mail.WinUI/Controls/WinoMenuFlyout.cs

@@ -0,0 +1,32 @@
+using Microsoft.UI.Xaml.Controls;
+
+namespace Wino.Mail.WinUI.Controls;
+
+public partial class WinoMenuFlyout : MenuFlyout
+{
+    public WinoMenuFlyout()
+    {
+        Opening += OnOpening;
+    }
+
+    private void OnOpening(object? sender, object e)
+    {
+        foreach (var item in Items)
+        {
+            ApplyLanguage(item);
+        }
+    }
+
+    private static void ApplyLanguage(MenuFlyoutItemBase item)
+    {
+        MenuFlyoutLanguageHelper.Apply(item);
+
+        if (item is MenuFlyoutSubItem subItem)
+        {
+            foreach (var childItem in subItem.Items)
+            {
+                ApplyLanguage(childItem);
+            }
+        }
+    }
+}