Windows 8.1 Preview Product Guide for Developers

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Windows 8 delivers on the promise of a “no compromise” experience that’s great for productivity and mobility. Consumers no longer have to choose between productivity and fun – Windows 8 delivers both. Businesses finally have access to the full PC experience—easily managed in the enterprise, but ready for mobile. Windows 8 sets the standard for content creation and consumption in a mobile device, providing flexibility and unique capabilities.

Windows 8.1 Preview builds on the bold vision and solid foundation of Windows 8, evolving the platform to enable the next wave of app innovation. We listened to our customers and carefully eval‎uated telemetry data to make hardware, devices, and the user experience better. In Windows 8.1 Preview, apps continue to take center stage, introducing new ways to interact with the system and more opportunities for customers to immerse themselves in your content. Consumers and business users can experience Windows in ways that are familiar and comfortable, yet new and exciting.

The range of hardware supported by Windows 8.1 Preview is unprecedented. The user experience has evolved, increasing user engagement. The Windows Store continues to offer best-in-class economics while enabling new revenue opportunities, better merchandizing, and improved app discoverability. And new engineering principles and telemetry data facilitate platform advances across hardware, devices, and the user experience. And of course, Windows continues to offer developers a unique array of choices – choice of programming language (C#, C++, xxJavaScript, or VB), choice of presentation technology (XAML, HTML, or DirectX), and choice of business model via the Windows Store.

On this page

  Leading experiences and a great platform drive user engagement

  Internet Explorer 11: Touch the web

  Devices provide a world of choice

  Making money in the Windows Store

  Modern engineering enables the next wave of app innovation

Leading experiences and a great platform drive user engagement

We designed Windows 8.1 Preview to drive app use and engagement. We listened to our customers, and made the user experience simpler and more intuitive. Advances in the Windows Runtime and evolution of the Microsoft design principles help your apps look and run even better, while offering better performance and an improved user experience that’s more tightly integrated with Windows. Changes to our graphics rendering pipeline make games more immersive. New controls enable fresh experiences and existing controls work better and faster with Windows 8.1 Preview. And Internet Explorer 11 is the touch-optimized, standards-based browser built to take advantage of the new platform.

Windows 8 is a complete redesign of Windows. With access to the classic desktop as well as a new Start screen, Windows 8 introduced a modern experience for touch-centric, mobile app experiences. Windows Store apps are touch-friendly, but also work great with mouse and keyboard, and put app content before chrome. With Windows 8.1 Preview, we’ve refined the user experience to make it more familiar and natural, while keeping the focus on great apps.

Learn more about the updates to the user experience for Windows 8.1 Preview in the Windows 8.1 Preview Feature Guide.

Live tile improvements

Live tiles are more useful in Windows 8.1 Preview and offer greater flexibility. You can declare a live tile in the app manifest, and it starts updating immediately after a user installs an app- you no longer have to run the app before you receive updates. In addition, tiles support two new sizes: 70x70px and 310x310px, offering users some creativity when customizing their Windows Start screen. When creating secondary tiles, apps can offer more size and image choices so you can customize your Start screen immediately.

Live tiles using the new sizes

Programmatic access to Contacts and Calendar

With Windows 8.1 Preview, you get convenient APIs to interact with a user’s contacts and calendar. The Contacts API enables a source app to query the data store by email address or phone number, returning the Contact Card UI for the matching contact. It also defines contact related action types that can be used by apps that handle the target action. The Calendar API allows you to add appointments, replace appointments, remove appointments, and show the user’s default appointment provider app side-by-side with another appointment provider app programmatically.

New and improved controls

With new XAML and WinJS controls, you can create more beautiful and engaging apps with better performance than you’re used to.

XAML Controls

XAML developers benefit from following changes in Windows 8.1 Preview:

• Access to the new Hub control
• Support for a new Flyout control, as well as Date and Time picker controls
• Improved interoperation with DirectX with SwapChainPanel
• Better performance for GridView and ListView

HTML and xxJavaScript controls

Windows 8.1 Preview delivers these improvements for WinJS developers:

• Access to the new Hub control
• Support for a new WebView control, Item control, and Navigation bar
• ListView support of drag-and-drop operations

Hub control

The new Hub control, available to both XAML and WinJS developers, makes it easier for apps to use a hub-like navigation pattern, without managing multiple ListView controls. As a result, you can create consistent and familiar apps that use hub-like navigation more quickly.

WebView control

WebView is new for xxJavaScript developers, and shares a similar implementation across app models. Far more than just a simple <iframe>, the WebView control now supports navigation (Back, Forward, Stop, Reload, etc.), and provides better support for touch input.

In-app Search

The Search charm has evolved, enabling search of the entire system and the web. As a result, a new in-app Search control has been added for both XAML and WinJS. You get the exact same in-app search experience as Windows 8, only now Search is more easily discovered in your apps.

New window states

With Windows 8.1 Preview, there are now more ways to resize apps:

• App sizes are determined by the user with a minimum width of 500px, and apps can state in their manifest that they support a smaller minimum of 320px.
• More than two apps can share the screen at the same time, and a single app can also use multiple monitors. As a result, users are more productive, and apps work more efficiently together to complete complex tasks.
• Windows Store apps can remain open and in the foreground when another app is launched, sharing the screen and staying in memory, instead of moving to the background.

See the Windows 8.1 Preview Feature Guide for more detailed information on app sizing and Window states.

Windows Store apps sharing the screen in different sizes

Games and media are even better

Windows 8 ushered in a new era of immersive gaming with support for DirectX 11.1. Windows 8.1 Preview takes it further with extensive improvements to the graphics rendering pipeline for both 2D and 3D apps. We’ve improved media support too, by providing new formats and standards, as well as improving media playback and PlayTo.

DirectX enhancements

With Windows 8.1 Preview, we've made some changes to make your DirectX games look even better and run more smoothly.

• With GPU scaling, you can dynamically resize your frame buffer to keep your 3D graphics smooth, while hardware multi-plane overlay support keeps your gorgeous 2D art and interfaces looking their best in native resolution.
• Tiled rendering gives you better performance from mobile and newer GPUs with little effort.
• The new low-level Direct3D Trim APIs for managing resources efficiently make transitions from different hardware states smoother and faster.
• A map default buffer operation lets you access a GPU’s default buffers directly from your app (if supported by the device) without the intermediate copy operation.
• Shaders can now be compiled and linked at runtime. Shaders can be procedurally composed inside your app, linked, and run without separate HLSL files.

Windows Store apps game developed with DirectX 11.1

Media optimization and playback

Windows 8.1 Preview introduces audio and video support for additional file formats, improved performance, and better battery life. The platform now supports playback of DRM protected CFF video, as well as Encrypted Media Extensions (EME) for HTML5. With EME, you can play protected content without plugins. Transcoding is now supported as a background task, so users can continue to use their PC during lengthy transcode sessions. And improvements to PlayTo ensure better compatibility by supporting more devices than Windows 8.

Internet Explorer 11: Touch the web

Internet Explorer 11 is the browser built for a touch-optimized web with Windows 8.1 Preview. With faster tab switching, improved Frequents list, and better navigation of favorite sites, IE11 is perfect for touch. You get real-world site performance for websites and Windows Store apps, and IE11 implements more web standards than ever. The web experience is integrated better with Windows, and IE11 provides industry-leading security, and redesigned developer tools that help you test across devices, browsers, and Windows Store apps.

Internet Explorer 11 in action

Better and safer integration with Windows

Websites get enhanced exposure on the Windows Start screen with customizable live tiles that connect to an RSS feed in minutes. You can add support for your website by adding simple meta tags to a page. Live tiles support four sizes (including large, wide, square, and tiny), and help users reflect their own personality on the Windows Start screen – placing the things they love at their fingertips.

You can create notifications that connect a site to an RSS feed in minutes. You can add support for your website by adding simple meta tags to a page.

With Internet Explorer 11, you get continued industry-leading secure and private browsing, including better password capture and management, a Do-Not-Track exception API, extension of Enhanced Protection Mode to the desktop, the Web Cryptography API, and improvements to SmartScreen.

Touch

For touch support in IE11, you get default handling for touch-based drag-and-drop, touch-based hover, and active link highlighting. Performance and responsiveness—especially with touch—continues to be a priority in IE11. The back swipe is an instant gesture, using smarter caching technologies that are detected in milliseconds when a user begins swiping back or forth. With prefetch and prerender, many forward navigations like getting to search results or to the next page in an article are also nearly instantaneous. IE11 uses responsive scrolling effects and more fine-tuned control of the panning and zooming experience on a site or Windows Store app. IE11 includes updates to Pointer Events that align Internet Explorer with the W3C Pointer Events specification, now in Candidate Recommendation.

Advancing the Web platform

IE11 improves compatibility and the implementation of web standards, such as a new user-agent string that helps sites just work using the existing code on a webpage.

For graphics and media, IE11 gives you:

• Super-fast 2D and 3D experiences powered by WebGL
• High-DPI rendering
• Device orientation tracking
• MPEG-DASH
• Canvas element improvements
• Encrypted Media Extension (EME)
• Screen orientation lock

You can take advantage of broad coverage of DOM L4 events, the xxJavaScript __proto__ property, XMLDocument, CSS3 backface-visibility, CSS3 border-image, mutation observers, and more. IE11 also incorporates ECMAScript 6 and builds further support for East Asian fonts and layout.

The best tools to build, debug, and tune web content

The newly redesigned F12 developer tools make it easier to develop and debug sites across browsers and Windows Store apps using xxJavaScript and HTML.

• The DOM Explorer tool offers a live view of the DOM and makes modifying DOM elements easier.
• The UI Responsiveness tool profiles webpages as they run, identifying where they slow down, and which processes take too much time.
• The Console and DOM Explorer tools provide autocomplete when typing elements.
• The Emulation tool previews what sites look like on everything from 240-pixel-wide mobile screens to 4K home theater screens.
• GPS emulation tests how mobile webpages respond anywhere in the world.
• The new Memory tool tracks memory usage over time, helping debug sluggish pages and crashes.

And with modern.IE, you can access online tools like free virtual machines of past versions of Windows and IE to help support the many versions of Internet Explorer.

F12 developer tools close up

See the Internet Explorer 11 Developer Guide for more information about IE11.

Devices provide a world of choice

The hardware and devices that run Windows 8.1 Preview are amazing! From the smallest tablets and convertibles to high powered ultra-books and PCs, the breadth of the Windows device market is unrivaled. This versatility gives you great opportunity to reach consumers with your apps. The Windows Runtime makes it easier than ever to take full advantage of hardware and device innovations without requiring you to write a custom driver.

Windows form factors

Unleashing the power of hardware and devices

Windows 8.1 Preview enables smaller, more secure, energy-efficient devices that give your customers great high-definition displays, seamless multimedia playback and great real-time communication experiences.

Wide range of device choices

Windows 8.1 Preview runs on a wide range of great hardware, so you can design and build devices from the smallest tablets and convertibles to high-powered ultra-books and PC's, all delivering the latest advances in screens, battery life, and performance.

High performance and longer battery life

Supporting a variety of processors and architectures, including the latest in low-power chipsets, Windows 8.1 Preview enables you to design and build lightweight mobile devices with high performance, energy efficiency, and longer battery life. With support for solid state hybrid drives, customers get faster boot, resume, and app launch times and increased storage capacity for less money. 

High resolution for all displays

It doesn't matter if you’re using a small or a large screen device, or wirelessly connecting to an external display, with high PPI, all your apps come to life in high resolution.

Connectivity wherever you go

Working on the go? Not a problem. Windows 8.1 Preview delivers a great always-on and always connected experience with better mobile broadband features and improved support for Bluetooth and NFC. New support for WiFi-Direct enables high bandwidth connections between devices using the same frequency range as Wi-Fi. With support for tethering, customers with mobile broadband can create a personal hotspot and share their connection with other devices.

Great camera capture and real-time communications

Windows 8.1 Preview elevates camera capture and real-time communication by supporting responsive picture capture and onboard video processing and streaming. The audio system gets a boost with support for front and back microphones, improved echo cancellation, and new audio capture. These changes drive the next generation of content creation, media optimization, playback, and sharing.

Safe and secure out-of-the-box

Windows 8.1 Preview devices have you covered for safety and security. Use BitLocker hardware encryption, support for virtual smart cards, and fingerprint recognition from the Windows 8.1 Preview biometric framework to get your system safe and secure.

Bringing the touch-first experience to non-touch systems

Inspire user confidence and bring the reality of a touch-first experience to non-touch systems using Direct Touch and precision touchpads.

Improved experience for Windows store device apps

Windows Store device apps are now easier to create and certify. With Windows 8.1 Preview:

• Device apps automatically start when a device is plugged in.
• Device operations can run as background tasks.
• You can update firmware even when an app is moved to the background and suspended.

Windows Runtime enhancements for hardware and devices

The Windows Runtime makes it easier than ever to take full advantage of hardware and device innovations with native support for protocol-based and device specific APIs. The Windows Runtime now provides native support for Human Interface Devices (HID), Universal Serial Bus (USB), and Bluetooth connectivity.

Human Interface Device (HID)

New Windows Runtime HID APIs (Windows.Devices.HumanInterfaceDevice) let your Windows Store app access devices that support the Human Interface Device (HID) protocol. When it was first developed, the HID protocol targeted devices like keyboards, mice, and joysticks and was designed to run over the USB transport. Today the HID protocol supports a significantly larger set of devices including keypads, digitizers, pen devices, sensors and barcode-scanners.  

Universal Serial Bus (USB)

Using the new USB namespace (Windows.Devices.USB), you can write a Windows Store app that talks to a peripheral device for which Microsoft doesn’t already provide an in-box class driver.

Bluetooth

Windows Store apps can use the new RFCOMM namespace (Windows.Devices.Bluetooth.Rfcomm) and GATT namespace(Windows.Devices.Bluetooth.GenericAttributeProfile) to access Bluetooth devices. These APIs provide access to the Bluetooth BR/EDR and Bluetooth LE transports.

Device specific APIs

Point of Service (POS), 3D Printers, and scanners are now natively supported by the Windows Runtime.

Point of Service (POS)

The new POS namespace (Windows.Devices.PointOfService) is the Microsoft implementation of the industry standard Unified Point of Service (UPOS) draft version 2.0 specification. It provides Windows Store apps with access to barcode scanners and magnetic stripe readers that comply with the UPOS standard and provides an easy migration path for POS developers to migrate desktop apps using Microsoft POS for .NET.

3D Printing

Windows 8.1 Preview adds support for 3D printing, allowing printers to seamlessly install with plug and play support, to queue jobs for printing, and to be managed by Windows. It also enables Windows Store apps to submit 3D print jobs to these devices.

Scanning

The new scanning namespace (Windows.Devices.Scan) contains the classes, interfaces, structures and other components built on top of the Windows Image Acquisition (WIA) COM APIs to provide native scanning support for Windows Store apps.

Developing drivers for Windows 8.1 Preview

Windows 8.1 Preview introduces a new driver framework (UMDF 2.0), which has been designed to improve system stability and make it easier for developers to create, test, and certify drivers.

Improved system reliability

UMDF 2.0 shares many of the methods previously restricted to KMDF. This means that driver developers can now load a driver into user mode, increasing the overall system stability and reliability without losing performance. In user mode, any fatal issue in the driver only causes the current device stack to stop, but not crash the whole system.

Easier programming model

UMDF 2.0 is designed to make developing drivers simpler. You can program using C and C++ programming models, a major change from earlier (1.x) versions of UMDF, which required you use COM.

All interfaces now shared between UMDF and KMDF have the same names, parameters, and structure definitions. This means you can use either UMDF or KMDF to compile any drivers with only shared functionality, or drivers that use conditional macros for calls only supported in one framework. 

Making money in the Windows Store

Windows 8 introduced the world to the Windows Store, a new way to discover and download apps for Windows. Windows 8.1 Preview evolves the Store experience to better highlight and showcase great apps for Windows. Improvements to the Windows Store user experience help consumers connect apps to their devices more simply. And the reach of Windows gives you access to an ever expanding audience of PC users around the world.

In addition to the best financial terms in the industry, the Windows Store offers leading discoverability, merchandising, and monetization options to help you build your global business. With Windows 8.1 Preview, app updates and new in-app offers get pushed to users automatically, to generate excitement and revenue for your apps.

We introduced the Windows Store with Windows 8 as a new way for consumers to discover great apps that run on Windows. With Windows 8.1 Preview, we’ve refreshed the experience to improve app discoverability and entice customers to come back again and again.

Better discoverability

The refreshed Windows Store is alive with activity, just like Windows. It’s home to an ever expanding catalog of fresh high quality apps, generating interest and excitement. Store recommendations are relevant and personal, pointing users to apps they’ll love. Discovering interesting apps is much easier, with enhancements to in-Store navigation and more exciting visuals that draw the user’s attention.

Windows Store for Windows 8.1 Preview

More merchandizing opportunities

We've designed the Windows Store to have the most merchandising opportunities for your apps. Store recommendations are personalized and relevant to you. Browsing the catalog of “New Releases” and “Popular Now” apps yields fresh and exciting apps every day. Related content and similar apps are front and center. And catalog views provide more info about apps to help build quicker connections with potential customers.

Richer visual assets to describe your apps

Tiles that represent your app in the Windows Store are improved and more visually striking. The Windows Store now supports three different tile sizes: a small tile (50x50px), used on the product description page, a medium tile (310x150px), and a large tile (a scaled-down screenshot of the app), which is used for personalized recommendations. In addition, topic pages and “Picks for you” are refreshed to take advantage of these new visual assets.

Windows Store "Picks for you"

Even better economics

Hard work pays off. We’ve designed the Windows Store with that in mind. The Store gives you the best financial opportunity in the industry, with the best developer split and access to millions of Windows users worldwide. With Windows 8.1 Preview, you have the best opportunity to make money on your app.

Stored value gift cards

With a stored value gift card, users who otherwise wouldn’t be able to get apps or in-app content from the Windows Store now can. The availability of gift cards also raises the profile of the Windows Store, opening a channel of prospective customers worldwide – especially in those locales where access to credit cards are uncommon. Customers can purchase redeemable codes online, or find a gift card in a brick-and-mortar store.

In-app consumables

Support for in-app consumables means that you can use the Windows Store to manage the sale and license of content that can be purchased, used, and then purchased again. Previously this support was only provided by 3^rd parties – now your app can use the familiar and trusted experience within the Windows Store to manage those transactions.

Larger catalogs

Windows Store apps now support larger catalogs of in-app items. Windows 8 limited the total number of available items to 100. Windows 8.1 Preview removes that limitation, enabling large catalogs that can grow over time.

Larger app package sizes

The Windows Store now supports larger package sizes (up to 8 gigabytes) and app bundles. App bundles help optimize the packaging and distribution of Windows Store app resource packages to users all around the world. Resource management in .appx packages is better optimized to streamline package sizing and distribution. These changes make it possible to build more exciting apps and immersive games for the Windows Store.

Certification enhancements

Changes to the Windows App Certification Kit make validating Windows Store apps easier and more efficient, leading to more higher-quality apps in the Windows Store. You can run this tool at any point during the development process, to help you identify problems early.

Selective test execution provides a way to identify specific tests that might be helpful as you develop, speed up test runs, and provide more targeted results.

Concurrent test execution means that tests run in parallel, rather than serially, which gets results more quickly. We’ve improved the UI, enhanced reporting, and added context sensitive help to improve kit usability, while providing more useful guidance to help interpret results.

Modern engineering enables the next wave of app innovation

Windows is engineered with innovation in mind. The platform is constantly evolving and improving, thanks to great customer feedback and user telemetry, enabling advances across hardware, devices, and the user experience.

Platform advances

We’ve engineered Windows 8.1 Preview to take advantage of the latest advancements, so you can do your best work on Windows.

Single sign-on

When a user logs on to a Windows 8.1 Preview device using their Microsoft Account, they’re instantly connected to the services and info they care about most. Windows 8.1 Preview provides an easy-to-use API that you can use to manage identity tokens and interact with web services. The net result for users is fewer requests to input credentials, as they stay authenticated across experiences.

PDF Support

Windows Store apps using C++ can now natively render PDF content directly to a DirectX drawing surface. This enables fast and fluid presentation of PDF-based content within a Windows Store app.

Text-to-speech

Windows Store apps now support the same text-to-speech technology as other Windows apps, using easily invoked Windows Runtime APIs.

WinJS Scheduler

The new WinJS Scheduler improves performance of WinJS apps by consolidating work queues and ensuring that high priority tasks get completed at the right time.

Networking improvements

The world is getting more connected, and apps that connect to a web service in the cloud are the norm, not the exception. Windows 8.1 Preview introduces a number of different improvements to the networking platform to help you create great connected apps on Windows.

Windows.Web.HTTP

With Windows 8.1 Preview, you get a new HTTP API for apps that target HTTP or REST-based services. This API offers more capabilities and better performance to support today’s connected apps. The HTTP capabilities are deeply integrated into Windows, and the API is flexible enough to support basic, site-specific, and advanced HTTP development scenarios.

Improved web authentication broker

With Windows 8.1 Preview and single sign-on, credentials are effectively shared from IE to the Web Authentication Broker, and to other services the user interacts with. The result is much improved credential roaming, allowing the user to truly sign-on once, without the need to manage separate credentials for each service they interact with.

HTTP prefetching

Nearly every app is connected to a service. With Windows 8.1 Preview, apps can take advantage of prefetching app content via HTTP before it’s actually needed—that way the content is ready immediately when the user wants it. Using this API, a background task can download content using a list of URI resources that should be prefetched. When the user launches the associated app, the content appears fresh, without a costly roundtrip to the server.

Improved background networking

New real-time communication (RTC) features improve the user experience for apps that use background networking. This support enables connected standby mode, which is a special power state for Windows devices that allows some apps on the lockscreen to receive network packets even when the PC is in a low-power state (standby).  Apps can use this feature to request, with user permission, that a download or upload continue when it might normally be interrupted. It also enables the “quiet hour” feature, which provides control over background tasks, file transfers, push notifications, and real time communications during hours the user chooses.

Powerful tools and all the resources you need

We’ve evolved the best developer tools in the industry to make you even more productive.

Visual Studio Express 2013 Preview for Windows 8.1 Preview

Visual Studio Express 2013 Preview for Windows 8.1 Preview is a free, lightweight version of the powerful Visual Studio integrated development environment (IDE). Visual Studio is packaged with Blend for Visual Studio, which includes tools to help you develop compelling user interfaces using either XAML or HTML5 and CSS3. Blend provides design-centric tooling to help you visually build complex user interfaces, including drag and drop Windows controls, design-time data binding, and in-place styling of data and control templates.

Windows Store app templates

All templates have been updated for the Windows 8.1 Preview release. Visual Studio 2013 Preview introduces the Hub App template which enables both xxJavaScript and XAML programmers to more easily take advantage of hub navigation.

Azure Mobile Services and Push Notification Wizard

Visual Studio 2013 Preview enables you to use an Azure Mobile Service as a backend for your app or add push notifications to your app using Azure Mobile Services.

Improved packaging

Resource packages and app bundles enable you to combine multiple image scales, sets of localized content, and Direct3D feature levels from the packaging wizard. Only the applicable set of resources will be downloaded to users’ device, allowing apps to download faster.

The packaging wizard also enables you to remotely validate your app on another device without the need to manually install Visual Studio or other software.  You can also reserve a name for your app right from the packaging wizard.

Coded UI test

Coded UI test allows you to use the cross-hair tool to write automated functional tests for testing Windows Store apps.

Editor productivity

The enhanced scrollbar is integrated into Visual Studio 2013 Preview to provide visual cues about your code structure, and brace completion saves you time by closing braces for you. NavigateTo was also added to help you reach to your destination faster.

Enhanced visual design

Visual Studio now offers a third visual theme, Blue, to complement the existing Light and Dark themes. All themes have also been enhanced to provide additional color and clarity in icons, and more contrast across the IDE.

Windows dev center

The new Windows dev center is chock full of resources, samples, and videos to help you build or transition your apps to Windows 8.1 Preview. It includes detailed walkthroughs for key developer scenarios, videos that help you quickly integrate new features, and hundreds of samples to jumpstart your projects.

And much more

Visual Studio 2013 preview also enhances the debugging experience, including mixed-mode debugging between xxJavaScript and C++, improved async debugging, improved xxJavaScript debugging, and improved DOM inspection tools for HTML and CSS. It also provides enhanced XAML design tools, new and improved performance tools for xxJavaScript and XAML, an improved xxJavaScript editing experience, and library and compiler improvements for Visual C++. For more info, see What's New in Visual Studio 2013.

Desktop app advancements

Windows is the only platform that’s optimized for productivity and mobility. The Windows desktop continues to add support so you can build outstanding productivity experiences that take full advantage of the latest hardware.

High DPI support

Windows 8.1 Preview improves support for high DPI monitors (200+ DPI). Apps can take advantage of high-DPI screens by listening for an event, and can change their pixel density if moved to a lower DPI monitor. This allows you to create more beautiful apps with higher resolution assets that look great on the latest hardware.

Direct composition

Improvements to DirectComposition enable smoother animations and effects for XAML developers, enabling parity with WinJS apps. With Windows 8.1 Preview, XAML developers can combine their app’s UI elements and create responsive and efficient animations that fulfill the promise of the “fast and fluid” Windows UI. In addition, with changes to DirectComposition, you can choose the best presentation framework for each element of your app’s UI, enabling hybrid presentation scenarios where XAML and HTML5 work hand-in-hand to deliver the most compelling user experience.

Direct manipulation

Updates to DirectManipulation APIs increase app responsiveness, and add ways to interact with apps.

• Cross-slide is a new gesture used for selection and for initiating drag-and-drop via touch.
• Autoscroll allows users to automatically scroll once they reach the end of visible content.
• Native support for panning and zooming via a touchpad helps users without touch displays take advantage of touch capabilities of Windows 8.1 Preview.

Simple and seamless update

Windows 8.1 Preview is delivered free to users via the Windows Store, so you can have high confidence that a majority of Windows users will update to Windows 8.1 Preview when it’s available. Upgrading apps to take advantage of functionality included with Windows 8.1 Preview is easy – and we have lots of content and tooling to help. The new Windows Dev Center is chock full of resources, samples, and helpful videos to help you transition your apps. And if you don’t have time to update your existing apps, don’t worry – your current apps will continue to work great with Windows 8.1 Preview.

Best of all, apps just work better with Windows 8.1 Preview. We’ve made many improvements to the infrastructure of Windows so apps launch and run faster, with greater capabilities than before. You can simply recompile your existing Window Store apps to take advantage of these improvements, or you can spend a bit more time and rebuild your app to get advances in the platform. When you make updates to your Windows 8.1 Preview apps they automatically get pushed to app users – no need to return to the Windows Store to download an update.

Windows 8 ushered in a new era for the PC – an era of nearly limitless hardware choices and form factors, an era of mobility, an era of new and exciting apps, and an era of new economic opportunity. Windows 8.1 Preview fulfills the promise of Windows 8, and takes the platform to new heights, enabling you to achieve your creative vision with the widest reach of any platform. Windows has already reached a billion people worldwide. Windows 8.1 Preview opens the door to the next billion customers, with a developer platform that’s evolved and improved from the ground up.