feat: Replace CefSharp with Microsoft Edge WebView2

CHANGELOG.md

@@ -5,6 +5,29 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [Unreleased]
+
+### Changed
+
+- Replace the embedded CefSharp/CEF browser with Microsoft Edge WebView2. The Syncthing UI is now rendered by
+  a real child window with GPU compositing, instead of being rasterised on the CPU and copied into a WPF
+  bitmap every frame, which makes scrolling and interaction dramatically smoother. This also removes roughly
+  150MB of CEF binaries from the distribution.
+- The embedded browser's data now lives in `data\webview2` (portable) or
+  `%LOCALAPPDATA%\SyncTrayzor\webview2` (installed). The old `cef\cache` folder can be deleted.
+
+### Removed
+
+- The Intel Xe graphics warning, and the CEF cache lockfile check that refused to start when a second
+  SyncTrayzor instance was running. Neither applies to WebView2. The "disable hardware rendering" setting
+  remains, and still applies to SyncTrayzor's own WPF interface.
+
+### Requirements
+
+- SyncTrayzor now requires the Microsoft Edge WebView2 Runtime. This ships with Windows 11 and is delivered to
+  Windows 10 via Microsoft Edge, so it is present on essentially all supported systems. If it is missing,
+  SyncTrayzor offers a link to the download page and continues to run Syncthing normally.
+
 ## [2.2.0] - 2026-07-18
 
 ### Added

installer/common.iss

@@ -37,8 +37,8 @@ PrivilegesRequired=admin
 PrivilegesRequiredOverridesAllowed=dialog
 CloseApplications=yes
 RestartApplications=no
-; If we try and close CefSharp.BrowserSubprocess.exe we'll fail - it doesn't respond well
-; However if we close *just* SyncTrayzor, that will take care of shutting down CefSharp and syncthing
+; msedgewebview2.exe processes are shared with other applications and must not be closed by us
+; However if we close *just* SyncTrayzor, that will take care of shutting down WebView2 and syncthing
 CloseApplicationsFilter=SyncTrayzor.exe
 TouchDate=current
 WizardStyle=modern

src/SyncTrayzor/App.Installed.config

@@ -11,15 +11,15 @@
       <DirectoryWatcherFolderExistenceCheckMilliseconds>3000</DirectoryWatcherFolderExistenceCheckMilliseconds>
       <IssuesUrl>https://github.com/GermanCoding/SyncTrayzor/issues</IssuesUrl>
       <EnableAutostartOnFirstStart>true</EnableAutostartOnFirstStart>
-      <CefRemoteDebuggingPort>2004</CefRemoteDebuggingPort>
+      <WebViewRemoteDebuggingPort>2004</WebViewRemoteDebuggingPort>
       <Variant>Installed</Variant>
       <SyncthingConnectTimeoutSeconds>600</SyncthingConnectTimeoutSeconds>
       <EnforceSingleProcessPerUser>true</EnforceSingleProcessPerUser>
       <PathConfiguration>
         <LogFilePath>%APPDATA%\SyncTrayzor\logs</LogFilePath>
         <ConfigurationFilePath>%APPDATA%\SyncTrayzor\config.xml</ConfigurationFilePath>
         <ConfigurationFileBackupPath>%APPDATA%\SyncTrayzor\config-backups</ConfigurationFileBackupPath>
-        <CefCachePath>%LOCALAPPDATA%\SyncTrayzor\cef\cache</CefCachePath>
+        <WebView2DataPath>%LOCALAPPDATA%\SyncTrayzor\webview2</WebView2DataPath>
         <SyncthingPath>%APPDATA%\SyncTrayzor\syncthing.exe</SyncthingPath>
         <SyncthingHomePath/>
       </PathConfiguration>

src/SyncTrayzor/App.Portable.config

@@ -11,15 +11,15 @@
       <DirectoryWatcherFolderExistenceCheckMilliseconds>3000</DirectoryWatcherFolderExistenceCheckMilliseconds>
       <IssuesUrl>https://github.com/GermanCoding/SyncTrayzor/issues</IssuesUrl>
       <EnableAutostartOnFirstStart>false</EnableAutostartOnFirstStart>
-      <CefRemoteDebuggingPort>2004</CefRemoteDebuggingPort>
+      <WebViewRemoteDebuggingPort>2004</WebViewRemoteDebuggingPort>
       <Variant>Portable</Variant>
       <SyncthingConnectTimeoutSeconds>600</SyncthingConnectTimeoutSeconds>
       <EnforceSingleProcessPerUser>true</EnforceSingleProcessPerUser>
       <PathConfiguration>
         <LogFilePath>logs</LogFilePath>
         <ConfigurationFilePath>data\config.xml</ConfigurationFilePath>
         <ConfigurationFileBackupPath>data\config-backups</ConfigurationFileBackupPath>
-        <CefCachePath>data\cef\cache</CefCachePath>
+        <WebView2DataPath>data\webview2</WebView2DataPath>
         <SyncthingPath>data\syncthing.exe</SyncthingPath>
         <SyncthingHomePath>data\syncthing</SyncthingHomePath>
       </PathConfiguration>

src/SyncTrayzor/Bootstrapper.cs

@@ -228,8 +228,8 @@ protected override void Configure()
 
             RecycleBinDeleter.Logger = s => LogManager.GetLogger(typeof(RecycleBinDeleter).FullName).Error(s);
 
-            // Workaround for Intel Xe processors, which mess up CefSharp unless we disable hardware
-            // rendering for WPF. See #606.
+            // Escape hatch for machines whose drivers don't get on with WPF's hardware rendering. This no
+            // longer affects the embedded browser: WebView2 renders in its own process and is unaffected.
             if (configuration.DisableHardwareRendering)
             {
                 RenderOptions.ProcessRenderMode = RenderMode.SoftwareOnly;

src/SyncTrayzor/Pages/BarAlerts/BarAlertsViewModel.cs

@@ -13,27 +13,21 @@ public class BarAlertsViewModel : Conductor<IBarAlert>.Collection.AllActive
         private readonly IAlertsManager alertsManager;
         private readonly ISyncthingManager syncthingManager;
         private readonly Func<ConflictResolutionViewModel> conflictResolutionViewModelFactory;
-        private readonly Func<IntelXeGraphicsAlertViewModel> intelXeGraphicsAlertViewModelFactory;
         private readonly IWindowManager windowManager;
         private readonly IConfigurationProvider configurationProvider;
-        private readonly GraphicsCardDetector graphicsCardDetector;
 
         public BarAlertsViewModel(
             IAlertsManager alertsManager,
             ISyncthingManager syncthingManager,
             Func<ConflictResolutionViewModel> conflictResolutionViewModelFactory,
-            Func<IntelXeGraphicsAlertViewModel> intelXeGraphicsAlertViewModelFactory,
             IWindowManager windowManager,
-            IConfigurationProvider configurationProvider,
-            GraphicsCardDetector graphicsCardDetector)
+            IConfigurationProvider configurationProvider)
         {
             this.alertsManager = alertsManager;
             this.syncthingManager = syncthingManager;
             this.conflictResolutionViewModelFactory = conflictResolutionViewModelFactory;
-            this.intelXeGraphicsAlertViewModelFactory = intelXeGraphicsAlertViewModelFactory;
             this.windowManager = windowManager;
             this.configurationProvider = configurationProvider;
-            this.graphicsCardDetector = graphicsCardDetector;
         }
 
         protected override void OnInitialActivate()
@@ -80,12 +74,6 @@ private void Load()
                 var vm = new PausedDevicesFromMeteringViewModel(pausedDeviceNames);
                 Items.Add(vm);
             }
-
-            var configuration = configurationProvider.Load();
-            if (!configuration.DisableHardwareRendering && !configuration.HideIntelXeWarningMessage && graphicsCardDetector.IsIntelXe)
-            {
-                Items.Add(intelXeGraphicsAlertViewModelFactory());
-            }
         }
 
         private void OpenConflictResolver()

src/SyncTrayzor/Pages/ThirdPartyComponentsViewModel.cs

@@ -55,21 +55,12 @@ public ThirdPartyComponentsViewModel(IProcessStartProvider processStartProvider)
                 },
                 new ThirdPartyComponent()
                 {
-                    Name = "CEF",
-                    Description = "Simple framework for embedding Chromium-based browsers in other applications",
-                    Homepage = "https://code.google.com/p/chromiumembedded",
-                    License = "Modified BSD License",
-                    Notes = "Browser component - used to display Syncthing UI",
-                    LicenseText = LoadLicense("CEF.txt")
-                },
-                new ThirdPartyComponent()
-                {
-                    Name = "CefSharp",
-                    Description = ".NET (WPF and Windows Forms) bindings for the Chromium Embedded Framework",
-                    Homepage = "https://github.com/cefsharp/CefSharp",
+                    Name = "WebView2",
+                    Description = "Microsoft Edge WebView2 SDK, for embedding web content in native applications",
+                    Homepage = "https://developer.microsoft.com/microsoft-edge/webview2/",
                     License = "New BSD License",
-                    Notes = "WPF adapter for CEF",
-                    LicenseText = LoadLicense("CefSharp.txt")
+                    Notes = "Browser component - used to display Syncthing UI",
+                    LicenseText = LoadLicense("WebView2.txt")
                 },
                 new ThirdPartyComponent()
                 {

src/SyncTrayzor/Pages/ViewerView.xaml

@@ -1,30 +1,17 @@
 <UserControl x:Class="SyncTrayzor.Pages.ViewerView"
              xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
              xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
-             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
-             xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
+             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+             xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
              xmlns:s="https://github.com/canton7/Stylet"
              xmlns:l="clr-namespace:SyncTrayzor.Localization"
-             xmlns:cefSharp="clr-namespace:CefSharp.Wpf;assembly=CefSharp.Wpf"
-             mc:Ignorable="d" 
+             mc:Ignorable="d"
              d:DesignHeight="300" d:DesignWidth="300">
     <Grid>
-        <ContentControl Content="{Binding WebBrowser}" UseLayoutRounding="True">
-            <ContentControl.Resources>
-                <Style TargetType="cefSharp:ChromiumWebBrowser">
-                    <Setter Property="ContextMenu">
-                        <Setter.Value>
-                            <ContextMenu>
-                                <MenuItem Header="{l:Loc Generic_Cut}" Command="{Binding WebBrowser.CutCommand}"/>
-                                <MenuItem Header="{l:Loc Generic_Copy}" Command="{Binding WebBrowser.CopyCommand}"/>
-                                <MenuItem Header="{l:Loc Generic_Paste}" Command="{Binding WebBrowser.PasteCommand}"/>
-                            </ContextMenu>
-                        </Setter.Value>
-                    </Setter>
-                    <Setter Property="RenderOptions.BitmapScalingMode" Value="NearestNeighbor"/>
-                </Style>
-            </ContentControl.Resources>
-        </ContentControl>
+        <!-- WebView2 hosts a native child window, which paints over any WPF content in the same cell.
+             It therefore has to be collapsed whenever one of the messages below is showing. -->
+        <ContentControl Content="{Binding WebBrowser}" UseLayoutRounding="True"
+                        Visibility="{Binding ShowBrowser, Converter={x:Static s:BoolToVisibilityConverter.Instance}}"/>
 
         <TextBlock HorizontalAlignment="Center" VerticalAlignment="Center" Text="{l:Loc ViewerView_SyncthingStarting}"
                    Visibility="{Binding ShowSyncthingStarting, Converter={x:Static s:BoolToVisibilityConverter.Instance}}"