Preview channel release notes for the Windows App SDK

The preview channel provides a preview of the next upcoming stable release. There may be breaking API changes between a given preview channel release and the next stable release. Preview channel releases do not include experimental APIs.

Important links:

• If you'd like to upgrade an existing app from an older version of the Windows App SDK to a newer version, see Update existing projects to the latest release of the Windows App SDK.
• For documentation on preview releases, see Install tools for preview and experimental channels of the Windows App SDK.

Version 1.1 Preview 3 (1.1.0-preview3)

This is the latest release of the preview channel for version 1.1. It supports all preview channel features (see Features available by release channel).

In an existing app using Windows App SDK 1.0 Stable, you can update your Nuget package to 1.1.0-preview3 (see the Update a package section in Install and manage packages in Visual Studio using the NuGet Package Manager). Additionally, see Downloads for the Windows App SDK for the updated runtime and MSIX.

In addition to all of the Preview 2 features, the following sections describe new and updated features, limitations, and known issues for this release.

WinUI 3

Mica and Background Acrylic are now available for WinUI 3 applications.

For more information about these materials, check out Materials in Windows 11. Check out our sample code for applying Mica in C++ applications at Using a SystemBackdropController with WinUI 3 XAML and in C# applications on GitHub as part of the WinUI Controls Gallery.

Notifications

Fixed issues:

• In 1.1.0-preview1 and 1.1.0-preview2, some unpackaged apps will have seen their app icons incorrectly copied to AppData\LocalMicrosoftWindowsAppSDK. For this release, they will be copied to AppData\Local\Microsoft\WindowsAppSDK instead. To avoid leaking icons, you should manually delete the app icon at the incorrect path after updating to 1.1.0-preview3.
• App icon and app display name retrieval for app notifications via Shortcuts is now supported. This app icon will be prioritized over any icon specified in resource files.
• Support for push notifications for unpackaged apps has been restored (see Limitations for noted exception). We've introduced the PushNotificationManager::IsSupported API to check if your app supports push notifications.

Limitations:

• Notifications for an elevated unpackaged app is not supported. PushNotificationManager::IsSupported will not perform a check for elevated mode. However, we are working on supporting this in a future release.

MSIX packaging

We've enhanced MSIX adding new and extending existing functionality via the extension categories:

• windows.appExecutionAlias
• windows.customDesktopEventLog
• windows.dataShortcuts
• windows.fileTypeAssociation
• windows.fileTypeAssociation.iconHandler
• windows.folder
• windows.shortcut

These require the Windows App SDK framework package to be installed. See Downloads for the Windows App SDK to install the runtime.

Environment manager

API set that allows developers to add, remove, and modify environment variables without having to directly use the registry API.

Clarification from 1.1 Preview 1: Automatic removal of any environment variable changes when an app that used environment manager is uninstalled is only available for packaged apps. Additionally, reverting environment variable changes requires installation of the Windows App SDK framework package, see Downloads for the Windows App SDK for the runtime.

Other known limitations

Regressions from 1.1 Preview 2:

• For .NET apps using MRT Core APIs and WinUI apps that don't deploy with single-project MSIX:
  • RESW and image files that were added to the project as Existing Items and previously automatically included to the PRIResource and Content ItemGroups, respectively, won't be included in those ItemGroups. As a result, these resources won't be indexed during PRI generation, so they won't be available during runtime.
    • Workaround: Manually include the resources in the project file and remove them from the None ItemGroup.
    • Alternative workaround: When available, upgrade your apps' .NET SDK to 6.0.300. See Version requirements for .NET SDK for additional information.
• For .NET apps that don't deploy with single-project MSIX:
  • If a file is added to the Content ItemGroup twice or more, then there will be a build error.
    • Workaround: Delete the duplicate inclusion/s or set EnableDefaultContentItems to false in the project file.

Both regressions will be restored in the next stable release.

Version 1.1 Preview 2 (1.1.0-preview2)

This is the second release of the preview channel for version 1.1. It supports all preview channel features (see Features available by release channel).

In an existing app using Windows App SDK 1.0 Stable, you can update your Nuget package to 1.1.0-preview2 (see the Update a package section in Install and manage packages in Visual Studio using the NuGet Package Manager). Additionally, see Downloads for the Windows App SDK for the updated runtime and MSIX.

In addition to all of the Preview 1 features, the following sections describe new and updated features, limitations, and known issues for this release.

Notifications

Fixed issues:

• An app without package identity sending notifications will now see its app icon in the notification if the icon is a part of the app's resource. If the app resource has no icon, the Windows default app icon is used.
• A WinUI 3 app that's not running can now be background-activated via a notification.

Regression from 1.1 Preview 1: Push notifications support for unpackaged apps. Expected to be restored in the next release.

Known limitations:

• We've introduced the PushNotificationManager::IsSupported API to check if self-contained apps support push notifications. However, this API is not yet working as intended, so keep an eye out in the next preview release for full support of the IsSupported API.
• Some unpackaged apps will see their app icons incorrectly copied to AppData\LocalMicrosoftWindowsAppSDK. For the next release, they will be copied to AppData\Local\Microsoft\WindowsAppSDK instead. To avoid leaking icons, the developer should manually delete their app icon at the incorrect path after upgrading to the next release.
• App icon and app display name retrieval for notifications via Shortcuts is not supported. But we're working on supporting that in a future release.

Deployment

New features:

• MSIX-packaged apps can now force deploy the Windows App SDK runtime packages using the DeploymentManager.Initialize() API.
• The Bootstrapper API now includes new options for improved usability and troubleshooting. For more details, see Reference the Windows App SDK framework package at run time and Rich information on Bootstrap initalization failure.

Known limitations:

• Self-contained deployment is supported only on Windows 10, 1903 and above.

Windowing

For easier programming access to functionality that's implemented in USER32.dll (see Windows and messages), this release surfaces more of that functionality in AppWindow itself.

New features:

• Apps with existing windows have more control over how a window is shown, by calling AppWindow.ShowOnceWithRequestedStartupState—the equivalent of ShowWindow(SW_SHOWDEFAULT).
• Apps can show, minimize, or restore a window and specify whether the window should be activated or not at the time the call is made.
• Apps can now set a window's client area size in Win32 coordinates.
• We've added APIs to support z-order management of windows.
• Apps drawing custom titlebars with AppWindowTitleBar.ExtendsContentIntoTitleBar can set a PreferredTitleBarHeight option. You have a choice of a standard height titlebar, or a tall titlebar that provides more room for interactive content. See Title bar in the Fluent design guidelines for advice about when to use a tall titlebar.

Known limitations:

• Tall titlebar support is available only on Windows 11. We are working to bring this downlevel along with other custom titlebar APIs.

WinUI 3

Fixed issues:

• Fixed issue causing C# apps with WebView2 to crash on launch when the C/C++ Runtime (CRT) isn't installed by upgrading the WebView2 SDK from 1020.46 to 1185.39.
• Fixed issue causing some rounded corners to show a gradient when they should be a solid color. For more information see issue 6076 & issue 6194 on GitHub.
• Fixed issue where updated styles were missing from generic.xaml.
• Fixed layout cycle issue causing an app to crash when scrolling to the end of a ListView. For more information see issue 6218 on GitHub.

Performance

C# applications have several performance improvements. For more details, see the C#/WinRT 1.6.1 release notes.

Version 1.1 Preview 1 (1.1.0-preview1)

This is the first release of the preview channel for version 1.1. It supports all preview channel features (see Features available by release channel).

In an existing app using Windows App SDK 1.0 Stable, you can update your Nuget package to 1.1.0-preview1 (see the Update a package section in Install and manage packages in Visual Studio using the NuGet Package Manager). Additionally, see Downloads for the Windows App SDK for the updated runtime and MSIX.

The following sections describe new and updated features, limitations, and known issues for this release.

WinUI 3

Known issue: Users are unable to drop an element when drag-and-drop is enabled.

Elevated (admin) support

Using Windows App SDK 1.1 Preview 1, apps (including WinUI 3) will be able to run with elevated privilege.

Important limitations

• Currently available only on Windows 11. But we're evaluating bringing this support downlevel in a later release.

Known issues

• WinUI 3 apps crash when dragging an element during a drag-and-drop interaction.

Self-contained deployment

Windows App SDK 1.1 will introduce support for self-contained deployment. Our Deployment overview details the differences between framework-dependent and self-contained deployment, and how to get started.

Known issues:

• A C++ app that is MSIX-packaged needs to add the below to the bottom of their project file to workaround a bug in the self-contained .targets file that removes framework references to VCLibs:

  <PropertyGroup>
      <IncludeGetResolvedSDKReferences>true</IncludeGetResolvedSDKReferences>
  </PropertyGroup>
  
  <Target Name="_RemoveFrameworkReferences"
      BeforeTargets="_ConvertItems;_CalculateInputsForGenerateCurrentProjectAppxManifest">
      <ItemGroup>
          <FrameworkSdkReference Remove="@(FrameworkSdkReference)" Condition="'%(FrameworkSdkReference.SDKName)' == 'Microsoft.WindowsAppRuntime.1.1-preview1'" />
      </ItemGroup>
  </Target>
  

• Supported only on Windows 10, 1903 and above

Notifications

Developers of MSIX-packaged, sparse-packaged, and unpackaged apps can now send Windows notifications.

New features:

• Support for app notifications for packaged and unpackaged apps. Full details on GitHub
  • Developers can send app notifications, also known as toast notifications, locally or from their own cloud service.
• Support for push notification for packaged and unpackaged apps. Full details on GitHub
  • Developers can send raw notifications or app notifications from their own cloud service.

Limitations:

• Apps published as self-contained may not have push notifications support. Keep an eye out in the next preview release for an IsSupported() API to check for push notifications support.
• Apps that are not MSIX-packaged sending app notifications will not see their app icon in the app notification unless they are console applications. Console apps that are not MSIX-packaged should follow the patterns shown in the ToastNotificationsDemoApp sample.
• Windows App SDK runtime must be installed to support push notifications, see Downloads for the Windows App SDK for the installer.
• A WinUI 3 app that's not running can't be background-activated via a notification. But we're working on supporting that in a future release.

Environment manager

API set that allows developers to add, remove, and modify environment variables without having to directly use the registry API.

New features

• Provides automatic removal of any environment variables changes when an app that used environment manager is uninstalled.

Limitations

• Currently unavailable in C# apps. But we're evaluating bringing this feature to C# apps in a later release.

Other limitations and known issues

• If you're using C# with 1.1.0 Preview 1, then you must use one of the following .NET SDK versions at a minimum: .NET SDK 6.0.201, 6.0.103, 5.0.212, or 5.0.406. To upgrade your .NET SDK, you can update to the latest version of Visual Studio, or visit Download .NET.

Version 1.0 Preview 3 (1.0.0-preview3)

Preview 3 is the latest release of the preview channel for version 1.0 of the Windows App SDK. Preview 3 supports all preview channel features.

Download 1.0 Preview 3 Visual Studio extensions (VSIX)

From the table below you can download the Visual Studio extensions (VSIX) for the 1.0 Preview 3 release. For all versions, see Downloads for the Windows App SDK. If you haven't done so already, start by configuring your development environment, using the steps in Install tools for the Windows App SDK.

The extensions below are tailored for your programming language and version of Visual Studio.

1.0 Preview 3 downloads	Description
C# Visual Studio 2019 extension	Build C# apps with the Windows App SDK Visual Studio 2019 extension.
C++ Visual Studio 2019 extension	Build C++ apps with the Windows App SDK Visual Studio 2019 extension.
C# Visual Studio 2022 extension	Build C# apps with the Windows App SDK Visual Studio 2022 extension.
C++ Visual Studio 2022 extension	Build C++ apps with the Windows App SDK Visual Studio 2022 extension.
The .exe installer, and MSIX packages	Deploy the Windows App SDK with your app using the .exe installer, and MSIX packages.

The following sections describe new and updated features, limitations, and known issues for 1.0 Preview 3.

WinUI 3

We now support deploying WinUI 3 apps without MSIX packaging. See Create your first WinUI 3 project to configure your WinUI 3 application to support unpackaged deployment.

Important limitations

• Unpackaged WinUI 3 applications are supported only on Windows versions 1909 and later.
• Unpackaged WinUI 3 applications are supported on x86 and x64; arm64 support will be added in the next stable release.
• Single-project MSIX Packaging Tools for Visual Studio 2019 or Visual Studio 2022 is required for unpackaged apps.
• In an unpackaged app, you might receive a prompt to install .NET 3.5; if you do, then you can ignore it.

• Some APIs are not currently supported in unpackaged apps. We're aiming to fix this in the next stable release. A few examples:

• ListView, CalendarView, and GridView controls are using the incorrect styles, and we're aiming to fix this in the next stable release.

For more info, or to get started developing with WinUI 3, see:

Other limitations and known issues

• Unpackaged apps are not supported on Windows 10 version 1809. We're aiming to fix this in the next release in the stable channel.

• C# Single-project MSIX app doesn't compile if C++ UWP Tools aren't installed. If you have a C# Single-project MSIX project, then you'll need to install the C++ (v14x) Universal Windows Platform Tools optional component.

• This release introduces the Blank App, Packaged (WinUI 3 in Desktop) project templates for C# and C++. These templates enable you to build your app into an MSIX package without the use of a separate packaging project (see Package your app using single-project MSIX). These templates have some known issues in this release:

  • Missing Publish menu item until you restart Visual Studio. When creating a new app in both Visual Studio 2019 and Visual Studio 2022 using the Blank App, Packaged (WinUI 3 in Desktop) project template, the command to publish the project doesn't appear in the menu until you close and re-open Visual Studio.

  • Error when adding C++ static/dynamic library project references to C++ apps using Single-project MSIX Packaging. Visual Studio displays an error that the project can't be added as a reference because the project types are not compatible.

  • Error when referencing a custom user control in a class library project. The application will crash with the error that the system can't find the path specified.

  • C# or C++ template for Visual Studio 2019. When you try to build the project, you'll encounter the error "The project doesn't know how to run the profile project name". To resolve this issue, install the Single-project MSIX Packaging Tools extension.

  • C# template for Visual Studio 2019 and Visual Studio 2022. In Visual Studio when you Start Debugging or Start Without Debugging, if your app doesn't deploy and run (and there's no feedback from Visual Studio), then click on the project node in Solution Explorer to select it, and try again.

  • C# template for Visual Studio 2019 and Visual Studio 2022. You will encounter the following error when you try to run or debug your project on your development computer: "The project needs to be deployed before we can debug. Please enable Deploy in the Configuration Manager." To resolve this issue, enable deployment for your project in Configuration Manager. For detailed instructions, see the Create your first WinUI 3 project.

  • C++ template for Visual Studio 2022 version 17.0 releases up to Preview 4. You will encounter the following error the first time you try to run your project: "There were deployment errors". To resolve this issue, run or deploy your project a second time. This issue will be fixed in Visual Studio 2022 version 17.0 Preview 7.

• No support for Any CPU build configuration: When adding the Windows App SDK to an existing .NET application or component that supports Any CPU, you must specify the desired architecture: x86, x64 or arm64.

• C# projects using 1.0 Preview 3 must use the following .NET SDK: .NET 5 SDK version 5.0.400 or later if you're using Visual Studio 2019 version 16.11.

• An alternative to DispatcherQueue.TryEnqueue (for resuming execution on the dispatcher queue thread) is to use the resume_foreground helper function in the Windows Implementation Library (WIL):

  1. Add a reference to your project to the Microsoft.Windows.ImplementationLibrary NuGet package.
  2. Add #include <wil/cppwinrt_helpers.h> to your pch.h.
  3. Add #include <winrt/Microsoft.UI.Dispatching.h> to your pch.h.
  4. Now co_await wil::resume_foreground(your_dispatcherqueue);.

Important issue impacting 1.0 Preview 1 and Preview 2

Version 1.0 Preview 1 and Preview 2 of the Windows App SDK includes a mechanism to clean up any environment variable changes made by a packaged app when that app is uninstalled. This feature is in an experimental state, and the first release includes a known bug that can corrupt the system PATH environment variable.

Preview 1 and Preview 2 corrupts any PATH environment variable that contains the expansion character %. This happens whenever any packaged app is uninstalled, regardless of whether that app uses the Windows App SDK.

Also see PATH environment variable corruption issue.

Details

The system PATH entry is stored in the Path value in the following key in the Windows Registry:

Computer\HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Environment

If you launch the Registry Editor (regedit.exe), then you can copy and paste the path above into the breadcrumb bar (immediately below the menu bar), and press Enter to locate the key.

The Path value of that key should be of type REG_EXPAND_SZ, but the bug changes it to REG_SZ. And that makes the system PATH environment variable unusable if it contains the variable expansion character %.

Affected releases

Mitigation

To get your machine back into a good state, take the following steps:

1. Check whether the PATH in the Registry is corrupt and, if so, reset it by running the script below.

   You can accomplish step 1 with the following Windows PowerShell script (PowerShell Core won't work). Run it elevated.

   # This script must be run from an elevated Windows PowerShell
   # window (right-click Windows PowerShell in the Start menu,
   # and select Run as Administrator).
   
   # If the PATH in the Registry has been set to REG_SZ, then delete
   # it, and recreate it as REG_EXPAND_SZ.
   
   $EnvPath = 'Registry::HKLM\System\CurrentControlSet\Control\Session Manager\Environment'
   $Environment=Get-Item $EnvPath
   $PathKind = $Environment.GetValueKind('Path')
   
   if ($PathKind -ne 'ExpandString') {
     $Path = $Environment.GetValue('Path')
     Remove-ItemProperty $EnvPath -Name Path
     New-ItemProperty $EnvPath -Name Path -PropertyType ExpandString -Value $Path
   }
   

2. Uninstall all apps that use the Windows App SDK 1.0 Preview1 or Preview2 (see the script below).

3. Uninstall the Windows App SDK 1.0 Preview1/Preview2 packages, including the package that contains the bug (see the script below).

   You can accomplish steps 2 and 3 with the following Windows PowerShell script (PowerShell Core won't work). Run it elevated.

   # This script must be run from an elevated Windows PowerShell
   # window (right-click Windows PowerShell in the Start menu,
   # and select Run as Administrator).
   
   # Remove the Windows App SDK 1.0 Preview1/2, and all apps that use it.
   
   $winappsdk = "Microsoft.WindowsAppRuntime.1.0-preview*"
   Get-AppxPackage | Where-Object { $_.Dependencies -like $winappsdk } | Remove-AppxPackage
   Get-AppxPackage $winappsdk | Remove-AppxPackage
   

Fix in Windows App SDK 1.0 Preview 3

The feature causing the PATH environment variable to be corrupted will be removed in the upcoming Windows App SDK 1.0 Preview 3 release. It might be reintroduced at a later date, when all bugs have been fixed and thoroughly tested.

We recommend using version 1.0 Preview 3.

Version 1.0 Preview 2 (1.0.0-preview2)

This is the latest release of the preview channel for version 1.0. It supports all preview channel features.

The following sections describe new and updated features, limitations, and known issues for this release.

WinUI 3

New updates:

• Controls have been updated to reflect the latest Windows styles from WinUI 2.6.
• Single-project MSIX is supported.
• WinUI 3 package can now target build 17763 and above. See issue #921 for more info.
• In-app toolbar is supported. However, the in-app toolbar and existing Hot Reload/Live Visual Tree support require the upcoming Visual Studio 17.0 Preview 5 release, available later in October.

Bug fixed: WebView2Runtime text is now localized.

For more info or to get started developing with WinUI 3, see:

Windowing

This release introduces updates to the AppWindow class. There are no major new features added in this release, but there are changes to method names, properties, and some return values have been removed. See the documentation and samples for detailed updates. If you worked with AppWindow in the 1.0 Experimental or 1.0 Preview 1 releases, expect some changes to your code.

New updates:

• The AppWindowConfiguration class has been removed. The properties of this class is now available on the AppWindow itself, or on the Presenter classes.
• Most bool return values for the WinRT API methods in this space has been removed and are now void since these methods would always succeed.
• The C# ImportDll calls are no longer needed for GetWindowIdFromWindow and GetWindowFromWindowId. Use the .NET wrapper methods available in the Microsoft.UI.Win32Interop class instead.

Important limitations:

• The Windows App SDK does not currently provide methods for attaching UI framework content to an AppWindow; you're limited to using the HWND interop access methods.
• Window title bar customization works only on Windows 11. Use the IsCustomizationSupported method to check for title bar customization feature support. We intend to bring this functionality down-level.

For more info, see Manage app windows.

Input

New updates:

• Improved support for precision touchpad input.

Important limitations:

• All PointerPoint static factory functions have been removed: GetCurrentPoint, GetCurrentPointTransformed, GetIntermediatePoints, and GetIntermediatePointsTransformed.
• The Windows App SDK does not support retrieving PointerPoint objects with pointer IDs. Instead, you can use the PointerPoint member function GetTransformedPoint to retrieve a transformed version of an existing PointerPoint object. For intermediate points, you can use the PointerEventArgs member functions GetIntermediatePoints and GetTransformedIntermediatePoints. See the documentation for additional details.

MRT Core

New updates:

• App developers can now opt out an image file or a RESW file from being indexed in the PRI file in .NET projects. See issue 980 for more info.

Important limitations:

• In .NET projects, resource files copy-pasted into the project folder aren't indexed on F5 if the app was already built. As a workaround, rebuild the app. See issue 1503 for more info].
• In .NET projects, existing resource files added from an external folder aren't indexed without manual setting of the Build Action. To work around this issue, set the Build Action in Visual Studio: Content for image files and PRIResource for RESW files. See issue 1504 for more info.

Deployment for unpackaged apps

New features:

• Windows App SDK 1.0 Preview 2 introduces a .NET wrapper for the bootstrapper API. The bootstrapper API is a set of native C/C++ functions that unpackaged apps must use to dynamically take a dependency on the Windows App SDK framework package at run time. The .NET wrapper provides an easier way to call the bootstrapper API from .NET apps, including Windows Forms and WPF apps. The .NET wrapper for the bootstrapper API is available in the Microsoft.WindowsAppRuntime.Bootstrap.Net.dll assembly, which is local to your app project. For more info about the .NET wrapper, see .NET wrapper library.
• Packaged apps can now use the deployment API to get the main and singleton MSIX packages installed on the machine. The main and singleton packages are part of the framework package that is installed with the app, but due to a limitation with the Windows application model, packaged apps will need to take this additional step in order to get those packages installed. For more info about how the deployment API works, see the deployment guide for packaged apps.

Important limitations:

• The .NET wrapper for the bootstrapper API only is only intended for use by unpackaged .NET applications to simplify access to the Windows App SDK.
• Only MSIX packaged apps that are full trust or have the packageManagement restricted capability have the permission to use the deployment API to install the main and singleton package dependencies. Support for partial-trust packaged apps will be coming in later releases.
• When F5 testing an x86 app which uses the DeploymentManager.Initialize method on an x64 system, ensure that the x64 framework is first installed by running the WindowsAppRuntimeInstall.exe. Otherwise, you will encounter a NOT_FOUND error due to Visual Studio not deploying the x64 framework, which normally occurs through Store deployment or sideloading.

App lifecycle

Most of the App Lifecycle features already exist in the UWP platform, and have been brought into the Windows App SDK for use by desktop app types, especially unpackaged Console apps, Win32 apps, Windows Forms apps, and WPF apps. The Windows App SDK implementation of these features cannot be used in UWP apps, since there are equivalent features in the UWP platform itself.

Non-UWP apps can also be packaged into MSIX packages. While these apps can use some of the Windows App SDK App Lifecycle features, they must use the manifest approach where this is available. For example, they cannot use the Windows App SDK RegisterForXXXActivation APIs and must instead register for rich activation via the manifest.

All the constraints for packaged apps also apply to WinUI 3 apps, which are MSIX-packaged, and there are additional considerations as described below.

Important considerations:

• Rich activation: GetActivatedEventArgs

  • Unpackaged apps: Fully usable.
  • Packaged apps: Usable, but these apps can also use the platform GetActivatedEventArgs. Note that the platform defines Windows.ApplicationModel.AppInstance whereas the Windows App SDK defines Microsoft.Windows.AppLifecycle.AppInstance. And while UWP apps can use the ActivatedEventArgs classes, such as FileActivatedEventArgs and LaunchActivatedEventArgs, apps that use the Windows App SDK AppLifecycle feature must use the interfaces not the classes (e.g, IFileActivatedEventArgs, ILaunchActivatedEventArgs, and so on).
  • WinUI 3 apps: WinUI 3's App.OnLaunched is given a Microsoft.UI.Xaml.LaunchActivatedEventArgs, whereas the platform GetActivatedEventArgs returns a Windows.ApplicationModel.IActivatedEventArgs, and the WindowsAppSDK GetActivatedEventArgs returns a Microsoft.Windows.AppLifecycle.AppActivationArguments object which can represent a platform LaunchActivatedEventArgs.
  • For more info, see Rich activation.

• Register/Unregister for rich activation

  • Unpackaged apps: Fully usable.
  • Packaged apps: Not usable use the app's MSIX manifest instead.
  • For more info, see Rich activation.

• Single/Multi-instancing

  • Unpackaged apps: Fully usable.
  • Packaged apps: Fully usable.
  • WinUI 3 apps: If an app wants to detect other instances and redirect an activation, it must do so as early as possible, and before initializing any windows, etc. To enable this, the app must define DISABLE_XAML_GENERATED_MAIN, and write a custom Main (C#) or WinMain (C++) where it can do the detection and redirection.
  • RedirectActivationToAsync is an async call, and you should not wait on an async call if your app is running in an STA. For Windows Forms and C# WinUI 3 apps, you can declare Main to be async, if necessary. For C++ WinUI 3 and C# WPF apps, you cannot declare Main to be async, so instead you need to move the redirect call to another thread to ensure you don't block the STA.
  • For more info, see App instancing.

• Power/State notifications

  • Unpackaged apps: Fully usable.
  • Packaged apps: Fully usable.
  • For more info, see Power management.

Known issue:

File Type associations incorrectly encode %1 to be %251 when setting the Verb handler's command line template, which crashes unpackaged Win32 apps. You can manually edit the Registry value to be %1 instead as a partial workaround. If the target file path has a space in it, then it will still fail and there is no workaround for that scenario.

Other limitations and known issues

• Version 1.0 Preview 1 and Preview 2 contain a critical bug. If you’ve already installed one of these previews, see how to resolve the issue. We recommend using version 1.0 Preview 3 instead.

• This release introduces the Blank App, Packaged (WinUI 3 in Desktop) templates for C# and C++ projects. These templates enable you to build your app into an MSIX package without the use of a separate packaging project. These templates have some known issues in this release:

  • C# template for Visual Studio 2019. You will encounter the error when you try to build the project: "The project doesn't know how to run the profile project name". To resolve this issue, install the Single-project MSIX Packaging Tools extension.

  • C# template for Visual Studio 2019 and Visual Studio 2022. You will encounter the following error when you try to run or debug your project on your development computer: "The project needs to be deployed before we can debug. Please enable Deploy in the Configuration Manager." To resolve this issue, enable deployment for your project in Configuration Manager. For detailed instructions, see the Create your first WinUI 3 project.

  • C++ template for Visual Studio 2019 and Visual Studio 2022. In this release, these projects are restricted to calling the subset of Win32 APIs that can be called by UWP apps. The Blank App, Packaged with WAP (WinUI 3 in Desktop) template is not affected by this issue.

  • C++ template for Visual Studio 2022 version 17.0 releases up to Preview 4. You will encounter the following error the first time you try to run your project: "There were deployment errors". To resolve this issue, run or deploy your project a second time. This issue will be fixed in Visual Studio 2022 version 17.0 Preview 5.

• Push notifications API (Microsoft.Windows.PushNotifications namespace) incorrectly included in the 1.0 Preview 2 release. This is still an experimental feature, and to you use it you must install the 1.0 Experimental release instead. This feature will be removed from the upcoming 1.0 Stable release.

• App lifecycle API (Microsoft.Windows.AppLifecycle namespace) incorrectly includes the Experimental attribute in the 1.0 Preview 2 release. The Experimental attribute will be removed from this API in the next release.

• No support for Any CPU build configuration: When adding the Windows App SDK to an existing .NET application or component that supports Any CPU, you must specify the desired architecture: x86, x64 or arm64.

• C# projects using 1.0 Preview 2 must use the following .NET SDK: .NET 5 SDK version 5.0.400 or later if you're using Visual Studio 2019 version 16.11.

• An alternative to DispatcherQueue.TryEnqueue (for resuming execution on the dispatcher queue thread) is to use the resume_foreground helper function in the Windows Implementation Library (WIL):

  1. Add a reference to your project to the Microsoft.Windows.ImplementationLibrary NuGet package.
  2. Add #include <wil/cppwinrt_helpers.h> to your pch.h.
  3. Add #include <winrt/Microsoft.UI.Dispatching.h> to your pch.h.
  4. Now co_await wil::resume_foreground(your_dispatcherqueue);.

Version 1.0 Preview 1 (1.0.0-preview1)

This is the first release of the preview channel for version 1.0. It supports all preview channel features.

The following sections describe new and updated features, limitations, and known issues for this release.

WinUI 3

This release of WinUI 3 is focused on building towards 1.0 Stable with bug fixes.

• New features: No new features in Preview 1.
• Fixed issues: For the full list of issues addressed in this release, see our GitHub repo.

For more info or to get started developing with WinUI 3, see:

Windowing

This release brings the Windowing API we introduced in Experimental 1 to a Preview state. There are no major new features areas in this release as it is focused on bugfixes, stability, and adjustments to the API signature. The noteworthy changes and additions are called out below.

New features:

• DisplayAreaWatcher has been added to the Windowing APIs. This allows a developer to observe changes in the display topology and enumerate DisplayAreas currently defined in the system.
• AppWindow now supports setting the window icon via the SetIcon method, and AppWindowTitleBar now supports selecting whether to show/hide the window icon along with the system menu via the IconShowOptions property.

Important limitations:

• This release of AppWindow is currently available only to Win32 apps (both packaged and unpackaged).
• The Windows App SDK does not currently provide methods for attaching UI framework content to an AppWindow; you're limited to using the HWND interop access methods.
• Window title bar customization works only on Windows 11. Use the IsCustomizationSupported method to check for title bar customization feature support. We intend to bring this functionality down-level.

For more info, see Manage app windows.

Input

This release brings some new features to the Input API. The noteworthy changes and additions are called out below.

New features and updates:

• PointerPredictor gives input latency sensitive applications such inking applications the ability to predict input point locations up to 15ms in the future to achieve better latency and smooth animation.
• PenDeviceInterop enables you to acquire a reference to the Windows.Devices.Input.PenDevice by using the FromPointerPoint method.
• InputCursor provides an explicit distinction between preset system cursor types and custom cursor types by removing the "Custom" type present in CoreCursor, and splitting the CoreCursor object into separate objects.
• Updates to InputCursor APIs.
• GestureRecognizer moved out of experimental to Microsoft.UI.Input.
• PointerPoint moved out of experimental to Microsoft.UI.Input.
• Mouse, touch, and pen input fully supported for WinUI 3 drag and drop.

Important limitations:

• This release of Input APIs has known issues with Windows version 1809.
• MRT Core is not yet supported by any subtype of InputCursor.
• Direct use of the platform SDK API Windows.UI.Core.CoreDragOperation will not work with WinUI 3 applications.
• PointerPoint properties RawPosition and ContactRectRaw were removed because they referred to non-predicted values, which were the same as the normal values in the OS. Use Position and ContactRect instead. Pointer prediction is now handled with the Microsoft.UI.Input.PointerPredictor API object.

MRT Core

Starting in version 1.0 Preview 1, MRT Core APIs have moved from the Microsoft.ApplicationModel.Resources namespace to the Microsoft.Windows.ApplicationModel.Resources namespace.

Other limitations and known issues

• Version 1.0 Preview 1 and Preview 2 contain a critical bug. If you’ve already installed one of these previews, see how to resolve the issue. We recommend using version 1.0 Preview 3 instead.

• Projects created by using the C++ Blank App, Packaged with WAP (WinUI 3 in Desktop) project template encounter the following build error by default: fatal error C1083: Cannot open include file: 'winrt/microsoft.ui.dispatching.co_await.h': No such file or directory. To resolve this issue, remove the following line of code from the pch.h file. This issue will be fixed in the next release.

  #include <winrt/microsoft.ui.dispatching.co_await.h>
  

• An alternative to DispatcherQueue.TryEnqueue (for resuming execution on the dispatcher queue thread) is to use the resume_foreground helper function in the Windows Implementation Library (WIL):

  1. Add a reference to your project to the Microsoft.Windows.ImplementationLibrary NuGet package.
  2. Add #include <wil/cppwinrt_helpers.h> to your pch.h.
  3. Add #include <winrt/Microsoft.UI.Dispatching.h> to your pch.h.
  4. Now co_await wil::resume_foreground(your_dispatcherqueue);.

• No support for Any CPU build configuration: The Windows App SDK is written in native code and thus does not support Any CPU build configurations. The WinUI 3 templates in Visual Studio only allow architecture-specific builds. When adding the Windows App SDK to an existing .NET application or component that supports Any CPU, you must specify the desired architecture: x86, x64 or arm64.

• .NET apps must target build 18362 or higher: Your TFM must be set to net5.0-windows10.0.18362 or higher, and your packaging project's <TargetPlatformVersion> must be set to 18362 or higher. For more info, see the known issue on GitHub.

• C# projects using 1.0 Preview 1 must use the following .NET SDK: .NET 5 SDK version 5.0.400 or later if you're using Visual Studio 2019 version 16.11.

• Unpackaged apps not supported on Windows 10 version 1809: This should be resolved in the next release.

Related topics