fixed webview for windows

Author: GabrielDuf

src/UniGetUI.Avalonia/App.axaml.cs

@@ -5,6 +5,7 @@
 using Avalonia.Markup.Xaml.Styling;
 using Avalonia.Platform;
 using Avalonia.Styling;
+using Avalonia.Threading;
 using UniGetUI.Avalonia.Infrastructure;
 using UniGetUI.Avalonia.Views;
 using UniGetUI.Avalonia.Views.DialogPages;
@@ -35,6 +36,21 @@ public override void Initialize()
 
     public override void OnFrameworkInitializationCompleted()
     {
+        if (OperatingSystem.IsWindows())
+        {
+            // Safety net for NativeWebView (WebView2) initialization failures thrown
+            // asynchronously on the dispatcher. Without this the app crashes; with it
+            // the Help page shows a fallback "Open in browser" button.
+            Dispatcher.UIThread.UnhandledException += (_, e) =>
+            {
+                if (e.Exception is InvalidOperationException { Message: var msg }
+                    && msg.Contains("child window for native control host"))
+                {
+                    e.Handled = true;
+                }
+            };
+        }
+
         if (ApplicationLifetime is IClassicDesktopStyleApplicationLifetime desktop)
         {
             if (OperatingSystem.IsMacOS())

src/UniGetUI.Avalonia/UniGetUI.Avalonia.csproj

@@ -20,6 +20,7 @@
         <AssemblyName>UniGetUI.Avalonia</AssemblyName>
         <ApplicationIcon>..\UniGetUI\icon.ico</ApplicationIcon>
         <AvaloniaUseCompiledBindingsByDefault>true</AvaloniaUseCompiledBindingsByDefault>
+        <ApplicationManifest Condition="$([MSBuild]::IsOSPlatform('Windows'))">app.manifest</ApplicationManifest>
     </PropertyGroup>
 
     <PropertyGroup Condition="'$(EnableAvaloniaDiagnostics)' == 'true'">

src/UniGetUI.Avalonia/Views/Pages/HelpPage.axaml.cs

@@ -9,43 +9,45 @@ public partial class HelpPage : UserControl, IEnterLeaveListener
 {
     private readonly HelpPageViewModel _viewModel;
     private string _pendingNavigation = HelpPageViewModel.HelpBaseUrl;
+    private bool _adapterReady;
 
     public HelpPage()
     {
         _viewModel = new HelpPageViewModel();
         DataContext = _viewModel;
         InitializeComponent();
 
-        WebViewControl.NavigationStarted += OnNavigationStarted;
-        WebViewControl.NavigationCompleted += OnNavigationCompleted;
-    }
-
-    private void OnNavigationStarted(object? sender, WebViewNavigationStartingEventArgs e)
-    {
-        NavProgressBar.IsVisible = true;
-    }
-
-    private void OnNavigationCompleted(object? sender, WebViewNavigationCompletedEventArgs e)
-    {
-        NavProgressBar.IsVisible = false;
-        _viewModel.CurrentUrl = WebViewControl.Source?.ToString() ?? HelpPageViewModel.HelpBaseUrl;
+        WebViewControl.NavigationStarted += (_, _) => NavProgressBar.IsVisible = true;
+        WebViewControl.NavigationCompleted += (_, _) =>
+        {
+            NavProgressBar.IsVisible = false;
+            _viewModel.CurrentUrl = WebViewControl.Source?.ToString() ?? HelpPageViewModel.HelpBaseUrl;
+            BackButton.IsEnabled = WebViewControl.CanGoBack;
+            ForwardButton.IsEnabled = WebViewControl.CanGoForward;
+        };
 
-        BackButton.IsEnabled = WebViewControl.CanGoBack;
-        ForwardButton.IsEnabled = WebViewControl.CanGoForward;
+        // WebView2 on Windows initializes asynchronously after the control is attached
+        // to the visual tree. Navigate() called before AdapterCreated is silently dropped.
+        // This mirrors WinUI's EnsureCoreWebView2Async() pattern.
+        WebViewControl.AdapterCreated += (_, _) =>
+        {
+            _adapterReady = true;
+            WebViewControl.Navigate(new Uri(_pendingNavigation));
+        };
     }
 
     public void NavigateTo(string uriAttachment)
     {
         string url = _viewModel.GetInitialUrl(uriAttachment);
-        if (WebViewControl.IsLoaded)
+        _pendingNavigation = url;
+        if (_adapterReady)
             WebViewControl.Navigate(new Uri(url));
-        else
-            _pendingNavigation = url;
     }
 
     public void OnEnter()
     {
-        WebViewControl.Navigate(new Uri(_pendingNavigation));
+        if (_adapterReady)
+            WebViewControl.Navigate(new Uri(_pendingNavigation));
     }
 
     public void OnLeave() { }

src/UniGetUI.Avalonia/Views/Pages/ReleaseNotesPage.axaml.cs

@@ -7,6 +7,7 @@ public partial class ReleaseNotesPage : UserControl, IEnterLeaveListener
 {
     private readonly ReleaseNotesPageViewModel _viewModel;
     private bool _loaded;
+    private bool _adapterReady;
 
     public ReleaseNotesPage()
     {
@@ -20,11 +21,21 @@ public ReleaseNotesPage()
             NavProgressBar.IsVisible = false;
             _viewModel.CurrentUrl = WebViewControl.Source?.ToString() ?? _viewModel.ReleaseNotesUrl;
         };
+
+        WebViewControl.AdapterCreated += (_, _) =>
+        {
+            _adapterReady = true;
+            if (!_loaded)
+            {
+                WebViewControl.Navigate(new Uri(_viewModel.ReleaseNotesUrl));
+                _loaded = true;
+            }
+        };
     }
 
     public void OnEnter()
     {
-        if (!_loaded)
+        if (!_loaded && _adapterReady)
         {
             WebViewControl.Navigate(new Uri(_viewModel.ReleaseNotesUrl));
             _loaded = true;

src/UniGetUI.Avalonia/app.manifest

@@ -7,12 +7,18 @@
 
   <compatibility xmlns="urn:schemas-microsoft-com:compatibility.v1">
     <application>
-      <!-- A list of the Windows versions that this application has been tested on
-           and is designed to work with. Uncomment the appropriate elements
-           and Windows will automatically select the most compatible environment. -->
-
-      <!-- Windows 10 -->
+      <!-- Windows 10 and Windows 11 -->
       <supportedOS Id="{8e0f7a12-bfb3-4fe8-b9a5-48fd50a15a9a}" />
     </application>
   </compatibility>
+
+  <!-- PerMonitorV2 DPI awareness is required for native child windows (e.g. WebView2).
+       Without this, Win32 NativeControlHost cannot create its HWND on Windows 10+. -->
+  <application xmlns="urn:schemas-microsoft-com:asm.v3">
+    <windowsSettings>
+      <dpiAwareness xmlns="http://schemas.microsoft.com/SMI/2016/WindowsSettings">PerMonitorV2, PerMonitor</dpiAwareness>
+      <dpiAware xmlns="http://schemas.microsoft.com/SMI/2005/WindowsSettings">true</dpiAware>
+    </windowsSettings>
+  </application>
+
 </assembly>