Harden Linux X11 hosting and tray lifecycle

.github/workflows/ci.yml

@@ -25,6 +25,8 @@
   WASDK_APP_PROJ_PATH:   '${{ github.workspace }}\samples\DesktopFlyouts.Wasdk.Sample.App\DesktopFlyouts.Wasdk.Sample.App.csproj'
   UWP_APP_PROJ_PATH:     '${{ github.workspace }}\samples\DesktopFlyouts.Uwp.Sample.App\DesktopFlyouts.Uwp.Sample.App.csproj'
   UNO_APP_PROJ_PATH:     '${{ github.workspace }}\samples\DesktopFlyouts.Uno.Sample.App\DesktopFlyouts.Uno.Sample.App.csproj'
+  UNO_LIB_PROJ_PATH:     '${{ github.workspace }}/src/DesktopFlyouts.Uno/DesktopFlyouts.Uno.csproj'
+  X11_TEST_PROJ_PATH:    '${{ github.workspace }}/tests/DesktopFlyouts.X11.Tests/DesktopFlyouts.X11.Tests.csproj'
 
 jobs:
   build-wasdk:
@@ -109,3 +111,33 @@
 
     - name: Build the sample app
       run: dotnet build $env:UNO_APP_PROJ_PATH -c $env:CONFIGURATION -a $env:PLATFORM --no-restore
+
+  build-test-uno-linux:
+    runs-on: ubuntu-latest
+
+    steps:
+    - name: Checkout the repository
+      uses: actions/checkout@v6
+      with:
+        fetch-depth: 0
+
+    - name: Setup .NET
+      uses: actions/setup-dotnet@v5
+      with:
+        dotnet-version: |
+          9.0.x
+          10.0.x
+
+    - name: Restore the Uno library
+      run: dotnet restore "$UNO_LIB_PROJ_PATH"
+
+    - name: Build the Uno library on Linux
+      run: dotnet build "$UNO_LIB_PROJ_PATH" -c Release --no-restore
+
+    - name: Run X11 unit tests
+      run: dotnet test "$X11_TEST_PROJ_PATH" -c Release
+
+    - name: Check changed-file whitespace
+      if: github.event_name == 'pull_request'
+      shell: bash
+      run: git diff --check "$(git merge-base HEAD "origin/$GITHUB_BASE_REF")"..HEAD

DesktopFlyouts.slnx

@@ -65,5 +65,8 @@
       <Platform Solution="*|x86" Project="x86" />
     </Project>
   </Folder>
+  <Folder Name="/tests/">
+    <Project Path="tests/DesktopFlyouts.X11.Tests/DesktopFlyouts.X11.Tests.csproj" />
+  </Folder>
 
 </Solution>

Directory.Build.targets

@@ -5,7 +5,7 @@
 		<!--  General properties  -->
 		<Configurations>Debug;Release</Configurations>
 		<Platforms>x86;x64;arm64</Platforms>
-		<RuntimeIdentifiers>win-x86;win-x64;win-arm64</RuntimeIdentifiers>
+		<RuntimeIdentifiers Condition="'$(MSBuildProjectName)' != 'DesktopFlyouts.Uno' And '$(IsTestProject)' != 'true'">win-x86;win-x64;win-arm64</RuntimeIdentifiers>
 
 	</PropertyGroup>
 </Project>

Directory.Packages.props

@@ -20,9 +20,12 @@
 		<PackageVersion Include="Microsoft.Windows.CsWin32" Version="0.3.275" />
 		<PackageVersion Include="Microsoft.Windows.CsWinRT" Version="2.2.0" />
 		<PackageVersion Include="Microsoft.Windows.SDK.BuildTools" Version="10.0.28000.1839" Condition="'$(MSBuildProjectName)' == 'DesktopFlyouts.Wasdk' Or '$(MSBuildProjectName)' == 'DesktopFlyouts.Wasdk.Sample.App'" />
+		<PackageVersion Include="Microsoft.NET.Test.Sdk" Version="18.9.0" />
 		<PackageVersion Include="Tmds.DBus.Protocol" Version="0.94.2" />
 		<PackageVersion Include="Tmds.DBus.Generator" Version="0.94.2" />
 		<PackageVersion Include="Svg.Skia" Version="3.2.1" />
+		<PackageVersion Include="xunit" Version="2.9.3" />
+		<PackageVersion Include="xunit.runner.visualstudio" Version="3.1.5" />
 	</ItemGroup>
 
 </Project>

src/DesktopFlyouts.Shared/DesktopFlyout.cs

@@ -1319,7 +1319,11 @@ private void HostWindow_SystemSettingsChanged(object? sender, EventArgs e)
         }
 
         /// <inheritdoc/>
+#if HAS_UNO
+        public new void Dispose()
+#else
         public void Dispose()
+#endif
         {
             if (_disposed)
                 return;
@@ -1349,6 +1353,9 @@ public void Dispose()
             _host?.Dispose();
             IsOpen = false;
 
+#if HAS_UNO
+            base.Dispose();
+#endif
             GC.SuppressFinalize(this);
         }
     }

src/DesktopFlyouts.Shared/DesktopFlyoutIsland.cs

@@ -117,7 +117,7 @@ private void DesktopFlyoutIsland_LayoutUpdated(object? sender, object e)
 
         private void UpdateTemplateSettings()
         {
-#if WASDK && !HAS_UNO
+#if WASDK
             TemplateSettings.BackdropCornerRadius = new(
                 GetBackdropCornerRadius(CornerRadius.TopLeft),
                 GetBackdropCornerRadius(CornerRadius.TopRight),
@@ -126,12 +126,13 @@ private void UpdateTemplateSettings()
 #endif
         }
 
-#if WASDK && !HAS_UNO
+#if WASDK
         private static double GetBackdropCornerRadius(double cornerRadius)
         {
             return Math.Max(0D, cornerRadius > 0D ? cornerRadius - 1D : 0D);
         }
 
+#if !HAS_UNO
         internal void UpdateOwnerBackdrop()
         {
             TemplateSettings.SystemBackdrop = _owner is not null && _owner.TryGetTarget(out var owner)
@@ -143,6 +144,7 @@ internal void ClearOwnerBackdrop()
         {
             TemplateSettings.SystemBackdrop = null;
         }
+#endif
 #endif
 
         private static bool AreClose(Size first, Size second)

src/DesktopFlyouts.Shared/DesktopFlyoutIslandTemplateSettings.cs

@@ -20,20 +20,22 @@ namespace DesktopFlyouts
     /// </remarks>
     public partial class DesktopFlyoutIslandTemplateSettings : DependencyObject
     {
-#if WASDK && !HAS_UNO
+#if WASDK
         /// <summary>
         /// Gets the corner radius used by backdrop elements inside the island template.
         /// </summary>
         /// <value>The owner island's corner radius reduced for its inner backdrop surface.</value>
         [GeneratedDependencyProperty]
         public partial CornerRadius BackdropCornerRadius { get; internal set; }
 
+#if !HAS_UNO
         /// <summary>
         /// Gets the library-created system backdrop used by backdrop elements inside the island template.
         /// </summary>
         /// <value>The owning flyout's generated system backdrop for this island.</value>
         [GeneratedDependencyProperty]
         public partial SystemBackdrop? SystemBackdrop { get; internal set; }
+#endif
 #endif
     }
 }

src/DesktopFlyouts.Shared/DesktopFlyouts.Shared.projitems

@@ -39,6 +39,8 @@
     <Compile Include="$(MSBuildThisFileDirectory)MouseScrollEventReceivedEventArgs.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Helpers\WindowHelpers.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Helpers\WindowHelpers.X11.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)Helpers\X11ScreenGeometry.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)Helpers\X11WindowActivation.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)XamlIslandApplication.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)XamlIslandHostWindow.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)XamlIslandHostWindow.X11.cs" />
@@ -47,4 +49,4 @@
     <AdditionalFiles Include="$(MSBuildThisFileDirectory)NativeMethods.json" />
     <AdditionalFiles Include="$(MSBuildThisFileDirectory)NativeMethods.txt" />
   </ItemGroup>
-</Project>
+</Project>

src/DesktopFlyouts.Shared/DesktopMenuFlyout.Uno.cs

@@ -309,7 +309,7 @@ private static double Clamp(double value, double min, double max)
         }
 
         /// <inheritdoc/>
-        public void Dispose()
+        public new void Dispose()
         {
             if (_disposed)
                 return;
@@ -332,6 +332,7 @@ public void Dispose()
             _host?.Dispose();
             IsOpen = false;
 
+            base.Dispose();
             GC.SuppressFinalize(this);
         }
     }

src/DesktopFlyouts.Shared/DesktopMenuFlyout.cs

@@ -7,6 +7,7 @@
 
 
 #if UWP
+using Windows.Graphics;
 using Windows.UI.Xaml;
 using Windows.UI.Xaml.Controls;
 using Windows.UI.Xaml.Markup;

src/DesktopFlyouts.Shared/Helpers/GeneralHelpers.X11.cs

@@ -1,92 +1,140 @@
 #if HAS_UNO
-// Real implementation: detects system theme via D-Bus org.freedesktop.portal.Settings.
+// Detects the system theme via D-Bus org.freedesktop.portal.Settings.
 // https://flatpak.github.io/xdg-desktop-portal/docs/doc-org.freedesktop.portal.Settings.html
 
-using System;
-using System.Threading.Tasks;
-using Tmds.DBus.Protocol;
 using DesktopFlyouts.DBus;
+using Tmds.DBus.Protocol;
+
+namespace DesktopFlyouts;
 
-namespace DesktopFlyouts
+internal static class GeneralHelpers
 {
-    internal static class GeneralHelpers
+    private const string Service = "org.freedesktop.portal.Desktop";
+    private const string ObjectPath = "/org/freedesktop/portal/desktop";
+
+    private static readonly object SyncRoot = new();
+    private static bool _isTaskbarLight;
+    private static Task? _initializationTask;
+    private static DBusConnection? _connection;
+    private static IDisposable? _settingsWatch;
+
+    static GeneralHelpers()
     {
-        private const string Service = "org.freedesktop.portal.Desktop";
-        private const string ObjectPath = "/org/freedesktop/portal/desktop";
+        AppDomain.CurrentDomain.ProcessExit += (_, _) => DisposeResources();
+    }
+
+    internal static event EventHandler? SystemSettingsChanged;
+
+    internal static bool IsTaskbarLight()
+    {
+        ThrowHelper.ThrowIfNotLinux();
+
+        lock (SyncRoot)
+        {
+            _initializationTask ??= InitializeAsync();
+            return _isTaskbarLight;
+        }
+    }
 
-        private static bool? _isTaskbarLight;
-        private static readonly object _lock = new();
-        private static bool _initialized;
+    internal static bool IsTaskbarColorPrevalenceEnabled()
+    {
+        // Linux desktop environments do not have a Windows-style "accent color on taskbar" setting.
+        return false;
+    }
 
-        internal static bool IsTaskbarLight()
+    private static async Task InitializeAsync()
+    {
+        DBusConnection? connection = null;
+        IDisposable? settingsWatch = null;
+        try
         {
-            ThrowHelper.ThrowIfNotLinux();
+            var sessionAddress = DBusAddress.Session;
+            if (sessionAddress is null)
+                return;
+
+            connection = new DBusConnection(sessionAddress);
+            await connection.ConnectAsync();
 
-            if (!_initialized)
+            var desktopService = new DBusService(connection, Service);
+            var settings = desktopService.CreateSettings(ObjectPath);
+            if (await settings.GetVersionAsync() < 2)
+                return;
+
+            var result = await settings.ReadOneAsync(
+                "org.freedesktop.appearance",
+                "color-scheme");
+            UpdateTheme(result.GetUInt32());
+
+            settingsWatch = await settings.WatchSettingChangedAsync(tuple =>
             {
-                _ = InitAsync().ConfigureAwait(false);
-            }
+                if (tuple is { Namespace: "org.freedesktop.appearance", Key: "color-scheme" })
+                    UpdateTheme(tuple.Value.GetUInt32());
+            });
 
-            lock (_lock)
+            lock (SyncRoot)
             {
-                return _isTaskbarLight ?? false;
+                _connection = connection;
+                _settingsWatch = settingsWatch;
+                connection = null;
+                settingsWatch = null;
             }
         }
-
-        internal static bool IsTaskbarColorPrevalenceEnabled()
+        catch
         {
-            // Linux desktop environments do not have a Windows-style "accent color on taskbar" setting.
-            return false;
+            // D-Bus or the portal is unavailable. Keep the dark fallback for this process.
         }
+        finally
+        {
+            settingsWatch?.Dispose();
+            connection?.Dispose();
+        }
+    }
 
-        private static async Task InitAsync()
+    private static void UpdateTheme(uint colorScheme)
+    {
+        // 0 = no preference, 1 = dark, 2 = light.
+        var isLight = colorScheme != 1;
+        var changed = false;
+        lock (SyncRoot)
         {
-            try
+            if (_isTaskbarLight != isLight)
             {
-                var sessionAddress = DBusAddress.Session;
-                if (sessionAddress is null)
-                    return;
-
-                var connection = new DBusConnection(sessionAddress);
-                await connection.ConnectAsync();
-
-                var desktopService = new DBusService(connection, Service);
-                var settings = desktopService.CreateSettings(ObjectPath);
-
-                var version = await settings.GetVersionAsync();
-                if (version < 2)
-                    return;
-
-                var result = await settings.ReadOneAsync("org.freedesktop.appearance", "color-scheme");
-                var colorScheme = result.GetUInt32();
-                // 0 = no preference, 1 = dark, 2 = light
-                lock (_lock)
-                {
-                    _isTaskbarLight = colorScheme != 1;
-                    _initialized = true;
-                }
-
-                _ = settings.WatchSettingChangedAsync(tuple =>
-                {
-                    if (tuple is { Namespace: "org.freedesktop.appearance", Key: "color-scheme" })
-                    {
-                        lock (_lock)
-                        {
-                            _isTaskbarLight = tuple.Value.GetUInt32() != 1;
-                        }
-                    }
-                });
-            }
-            catch
-            {
-                // D-Bus not available or portal not present; fall back to default (dark).
-                lock (_lock)
-                {
-                    _isTaskbarLight = false;
-                    _initialized = true;
-                }
+                _isTaskbarLight = isLight;
+                changed = true;
             }
         }
+
+        if (changed)
+            SystemSettingsChanged?.Invoke(null, EventArgs.Empty);
+    }
+
+    private static void DisposeResources()
+    {
+        IDisposable? settingsWatch;
+        DBusConnection? connection;
+        lock (SyncRoot)
+        {
+            settingsWatch = _settingsWatch;
+            connection = _connection;
+            _settingsWatch = null;
+            _connection = null;
+        }
+
+        try
+        {
+            settingsWatch?.Dispose();
+        }
+        catch
+        {
+        }
+
+        try
+        {
+            connection?.Dispose();
+        }
+        catch
+        {
+        }
     }
 }
 #endif