fix.修复了窗口问题，以及多次显示圆角调节选项的问题。

LanMountainDesktop.Tests/MaterialColorSettingsPageViewModelTests.cs

@@ -65,6 +65,22 @@ public sealed class MaterialColorSettingsPageViewModelTests
         Assert.Equal(1, facade.ThemeSaveCount);
     }
 
+    [Fact]
+    public void UserSelection_SystemMaterialModeRequestsRestart()
+    {
+        var facade = new FakeSettingsFacade(CreateThemeState(ThemeAppearanceValues.MaterialNone));
+        var materialService = new FakeMaterialColorService(CreateSnapshot(ThemeAppearanceValues.MaterialNone));
+        var viewModel = new MaterialColorSettingsPageViewModel(facade, materialService);
+        string? restartReason = null;
+        viewModel.RestartRequested += reason => restartReason = reason;
+
+        viewModel.SelectedSystemMaterialMode = viewModel.SystemMaterialModes.Single(option =>
+            option.Value == ThemeAppearanceValues.MaterialMica);
+
+        Assert.Equal(viewModel.SystemMaterialRestartMessage, restartReason);
+        Assert.False(string.IsNullOrWhiteSpace(restartReason));
+    }
+
     private static ThemeAppearanceSettingsState CreateThemeState(string materialMode)
     {
         return new ThemeAppearanceSettingsState(

LanMountainDesktop.Tests/SystemChromeModeTests.cs

@@ -0,0 +1,103 @@
+using Xunit;
+
+namespace LanMountainDesktop.Tests;
+
+public sealed class SystemChromeModeTests
+{
+    [Fact]
+    public void SettingsWindow_SystemChromeUsesNativeDecorations()
+    {
+        var source = ReadRepositoryFile("LanMountainDesktop", "Views", "SettingsWindow.axaml.cs");
+        var applyChromeMode = ExtractMethodSource(source, "ApplyChromeMode");
+        var onLoaded = ExtractMethodSource(source, "OnLoaded");
+
+        Assert.Contains("_useSystemChrome = useSystemChrome || OperatingSystem.IsMacOS();", applyChromeMode);
+        Assert.Contains("WindowDecorations = WindowDecorations.Full;", applyChromeMode);
+        Assert.Contains("ExtendClientAreaToDecorationsHint = !_useSystemChrome;", applyChromeMode);
+        Assert.Contains("ExtendClientAreaTitleBarHeightHint = _useSystemChrome ? 0d : CustomTitleBarHeight;", applyChromeMode);
+        Assert.Contains("TitleBar.ExtendsContentIntoTitleBar = !_useSystemChrome;", applyChromeMode);
+        Assert.Contains("WindowTitleBarHost.IsVisible = false;", applyChromeMode);
+        Assert.Contains("WindowTitleBarHost.IsVisible = true;", applyChromeMode);
+        Assert.DoesNotContain("TitleBar.ExtendsContentIntoTitleBar = true;", onLoaded);
+    }
+
+    [Fact]
+    public void ComponentEditorWindow_SystemChromeUsesNativeDecorations()
+    {
+        var source = ReadRepositoryFile("LanMountainDesktop", "Views", "ComponentEditorWindow.axaml.cs");
+        var applyChromeMode = ExtractMethodSource(source, "ApplyChromeMode");
+
+        Assert.Contains("var preferSystemChrome = useSystemChrome || OperatingSystem.IsMacOS();", applyChromeMode);
+        Assert.Contains("WindowDecorations = WindowDecorations.Full;", applyChromeMode);
+        Assert.Contains("ExtendClientAreaToDecorationsHint = false;", applyChromeMode);
+        Assert.Contains("ExtendClientAreaTitleBarHeightHint = 0d;", applyChromeMode);
+        Assert.Contains("CustomTitleBarHost.IsVisible = false;", applyChromeMode);
+        Assert.Contains("WindowDecorations = WindowDecorations.BorderOnly;", applyChromeMode);
+        Assert.Contains("ExtendClientAreaToDecorationsHint = true;", applyChromeMode);
+        Assert.Contains("CustomTitleBarHost.IsVisible = true;", applyChromeMode);
+    }
+
+    [Fact]
+    public void SavingSystemChromeSynchronizesWindowsPatcherState()
+    {
+        var source = ReadRepositoryFile("LanMountainDesktop", "Services", "Settings", "SettingsDomainServices.cs");
+
+        Assert.Contains("if (OperatingSystem.IsWindows())", source);
+        Assert.Contains("LanMountainDesktop.Platform.Windows.ChromePatchState.UseSystemChrome = state.UseSystemChrome;", source);
+    }
+
+    private static string ReadRepositoryFile(params string[] segments)
+    {
+        var directory = new DirectoryInfo(AppContext.BaseDirectory);
+        while (directory is not null)
+        {
+            var candidate = Path.Combine(new[] { directory.FullName }.Concat(segments).ToArray());
+            if (File.Exists(candidate))
+            {
+                return File.ReadAllText(candidate);
+            }
+
+            if (File.Exists(Path.Combine(directory.FullName, "LanMountainDesktop.slnx")))
+            {
+                break;
+            }
+
+            directory = directory.Parent;
+        }
+
+        throw new FileNotFoundException($"Could not locate repository file '{Path.Combine(segments)}'.");
+    }
+
+    private static string ExtractMethodSource(string source, string methodName)
+    {
+        var methodIndex = source.IndexOf($"private void {methodName}(", StringComparison.Ordinal);
+        if (methodIndex < 0)
+        {
+            methodIndex = source.IndexOf($"public void {methodName}(", StringComparison.Ordinal);
+        }
+
+        Assert.True(methodIndex >= 0, $"Could not locate method '{methodName}'.");
+
+        var braceIndex = source.IndexOf('{', methodIndex);
+        Assert.True(braceIndex >= 0, $"Could not locate method body for '{methodName}'.");
+
+        var depth = 0;
+        for (var i = braceIndex; i < source.Length; i++)
+        {
+            if (source[i] == '{')
+            {
+                depth++;
+            }
+            else if (source[i] == '}')
+            {
+                depth--;
+                if (depth == 0)
+                {
+                    return source.Substring(methodIndex, i - methodIndex + 1);
+                }
+            }
+        }
+
+        throw new InvalidOperationException($"Could not extract method '{methodName}'.");
+    }
+}