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Yet again, we’ve updated the Silverlight Client for Facebook for the Silverlight 4 release version.  In order to use the updated one, you must follow these instructions:

  • First, uninstall the previous version you have.  This can be done in Add/Remove Programs on Windows or by just deleting the app on Mac.
  • Ensure you have Silverlight 4 installed.  If you are using the development tools and have installed Silverlight 4 developer tools, that’s fine.  If you are not a developer, visit http://microsoft.com/getsilverlight to get the latest Silverlight 4 version (4.0.50401.0).
  • After you have Silverlight 4 installed, visit the app page and install it.

You should be good after this! 

So why so many uninstall/re-installs!?  I thought you had an auto-update mechanism!

We do!  With Silverlight 4 trusted applications, the update mechanism requires that your applications be signed in order to use the auto-update APIs.  We wanted to wait until SL4 released in order to provide a signed version (and our internal signing process didn’t allow signing the beta).  Now that we have a signed version, you’ll be prompted when an update has been installed for the app.  For more details on signing your Silverlight applications see:

Hope this helps!

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One of the features we are introducing in Silverlight 4 is a ‘silent install’ mechanism for out-of-browser applications.  Currently every out-of-browser application (trusted or not) starts from an in-browser mechanism.  In some instances where you want to deploy the app via managed desktop software or perhaps via CD-ROM, you don’t want to have to tell the user to start on an HTML page first.

Now I’m not going to write here about the merits of why you might want to do this other than to point out what I believe to be the 2 prominent scenarios: managed desktop deployment and CD/DVD distribution.  I know some of you might be thinking Well if it is a managed desktop environment, why not just use WPF then? – and I would pose the same question to the customer as well first.  But again, this post is to merely outline the capabilities and I’ll let you all debate the reasons :-)

The function still requires the Silverlight plugin to be installed (and requires Silverlight 4).  It would also require the ability to install out-of-browser applications (there is a possibility for an administrator to disable this feature).  Given those two requirements, the key tool at your disposal is sllauncher.exe.  This is installed with the plugin and is located at %ProgramFiles%\Microsoft Silverlight on the machine.

NOTE: The features I’m describing here are for Windows machines.  Out-of-browser applications on OSX are actually deployed as ‘apps’ (.app) versus how just the XAP is deployed on a Windows machine.  I’m investigating how to do something similar here with scripting on OSX, but I’m unfortunately not a Mac developer :-).

Let’s take a look at the required steps and a scenario.

The Setup

You’ll need to ensure that the plugin is installed as I mentioned earlier.  You’ll also want to have a copy of the XAP handy that you’ll want to be installing.  This would be the main XAP and would be the same one that would be in the Source parameter of the <object> tag where you normally would host this.

NOTE: Because “Program Files” is different on 32- and 64-bit machines you’ll want to make sure your script/installer can handle the determination of where the sllauncher.exe program will be.  Since it isn’t a native 64-bit app, it will be in “Program Files (x86)” on a 64-bit machine.  This sometimes can cause confusion because the %ProgramFiles% environment variable on 64-bit is the native program files directory and *not* the x86 one.

Your Silverlight XAP will already have to have been configured for out-of-browser and have the appropriate manifest information within it.

Once you have those you can move on to understanding the parameters.

The Options for Install

The sllauncher.exe program for install require at a minimum 2 options and I’ll suggest that you always use all 4 I will describe here.

/install:”path-toXAP-File” – this is the first and points to the XAP file you are wanting to install.  This might be on a network share, on the CD, or in an installer.  This is required.

/origin:”URI-to-origin” – this is the ‘origin’ of the XAP and is required.  Even though you might not be using auto-update features, etc. you must set this.  I actually recommend being smart about it and having the XAP on a real URI endpoint as well so that your origin is actually real.

/shortcut:desktop+startmenu – while this is optional, it actually seems silly not to include at least one – or your users will have a hard time launching your application!  You can use: desktop, startmenu, or desktop+startmenu (my recommendation).

/overwrite – this option confirms the XAP you are installing will overwrite any existing version currently there.  This is optional, but again, I think you should use it.

Let’s assume the following scenario using the Silverlight Client for Facebook application as an example.  I have the XAP (Silverface.xap) that I want to deploy.  I would use the following command:

   1: "%ProgramFiles%\Microsoft Silverlight\sllauncher.exe" 
   2:     /install:"Silverface.xap" 
   3:     /origin:"http://www.silverlight.net/content/samples/apps/facebookclient/ClientBin/Silverface.xap" 
   4:     /shortcut:desktop+startmenu /overwrite

This assumes that I’m calling this command from where the Silverface.xap is currently.  Notice that the origin parameter points to the XAP origin and not the site hosting it.  This is important.  This above command would install the app and create shortcuts.

Automatically Launching the App

So what if you wanted to also automatically launch the app after installing (i.e., the CD/DVD ‘autorun’ scenario).  You again would use sllauncher.exe to do this for you after you’ve installed the app.  Using our same sample above here would be the command:

   1: "%ProgramFiles%\Microsoft Silverlight\sllauncher.exe" 
   2:     /emulate:"Silverface.xap" 
   3:     /origin:"http://www.silverlight.net/content/samples/apps/facebookclient/ClientBin/Silverface.xap" 
   4:     /overwrite

Notice the emulate command.  This is the launcher.  Now you’ll notice that this isn’t the same command-line options if you looked at an installed applications’ created shortcuts.  Because the folder where the XAP gets installed is pretty random, we use the origin as the hint to the sllauncher.exe program to find the right app for us and start it up.  I’ve found that using /overwrite will also give a more consistent behavior.

Uninstalling the App

What if now you want to uninstall the app?  Perhaps the managed desktop admins deprecate an application or you want the CD/DVD experience to be a non-transient one and clean up when done.  The command again is simple:

   1: "%ProgramFiles%\Microsoft Silverlight\sllauncher.exe" 
   2:     /uninstall 
   3:     /origin:http://www.silverlight.net/content/samples/apps/facebookclient/ClientBin/Silverface.xap

Instead of the install parameter you use the uninstall parameter.  Again, notice the use of the origin parameter – this is critical in all these tasks.  The above command would remove the application and essentially does the same thing as the right-click Remove this application context menu option in Silverlight.

Using these commands in Installers

While I think those that actually have a need for this option will be using scripts and batch files, I do think some may want to include this in an installer experience.  The only option I can see for this is because you are also deploying some additional items along with your XAP (perhaps assets to the user’s document store that the app will use later like plugins or something).  Other than that if you are creating an installer simply to wrap the above methods, it might not seem wise.

Why, you ask?  Well if you think about it, your installer itself will stamp an entry into Windows as an installed application and Silverlight will also stamp an entry.  In our Facebook example, the Add/Remove Programs would show 2 “Silverlight for Facebook” entries (assuming we named our installer that as well).  This would likely confuse the user.  I’m not saying it isn’t impossible to do this nor is it difficult to manage, I just think it looks odd.

Regardless, if you are using something like InstallShield (FYI look for InstallShield LE in Visual Studio 2010…it’s very good) or the Visual Studio Setup projects, you can include a Custom Action to these installers.  The process would be a custom action *after* the install is complete because you need to locate the XAP to install.  Most setup programs are easy to use and provide pre-configured platform-specific environment variables you can use to map to things like the correct Program Files directory.

In the ideal situation you’re batch file/installer should check for the presence of Silverlight (and the correct version).  These can be done using file path verification or registry checking, both of which are outlined in the deployment guide whitepaper.

What about redistribution of Silverlight?  Right now we do not have broad redistribution rights for Silverlight.  You will still need to point users to where they can get the plugin so that they can be presented with the EULA and get the correct version for their platform.

If you do use the installer route, make sure that you account for clean un-installations as well!

Other insights and summary

You may be asking yourself if the user will be prompted here to install the application?  The answer is no.  Since this is essentially a command-line execution, the trust is implied here.  The user first has to knowingly type the command (not likely) or knowingly execute your install mechanism (batch file, installer, whatever).  These commands cannot be automatically run from the browser, for example.  For managed desktops, sure, these may be silently installed.  This is intended because in a managed desktop environment the software is, well, managed.  An elevated or normal-privileged application will install just the same using these methods.

As to the shortcuts (the /shortcut parameter being optional).  I think we’re going to fix that in some update.  Again, it’s a bit foolish to not provide one so consider it required :-).

If you find yourself in a situation needing this, hopefully it will come in useful.  I really think this is a helpful tool, but also a niche tool.  Those of you creating general consumer applications/sites will not benefit here really because you’ll likely start with an in-browser instance anyway.  But for those using managed desktop environments, or thinking about CD ‘autorun’ type situations, hopefully this information will come in useful.

This work is licensed under a Creative Commons Attribution By license.

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At the Microsoft Professional Developer (PDC) conference, Scott Guthrie announced the availability of Silverlight 4 Beta.

UPDATE (March 2010): Silverlight 4 RC made available!  Go read my updated post on what has changed after you read below about the core features.


That’s right, we’ve released an early beta of the next version of Silverlight.  It’s really amazing to think what the team is accomplishing at the pace they are accomplishing it!  Silverlight 3 released just over 3 months ago and here we are with yet another release full of features that our community has been asking for. 

This beta release is a developer release.  This means that this is a preview mostly for developers to understand the new features and continue to get feedback.  No “end-user” runtime is available for this release, nor is a “go-live” license for customers wishing to put their applications into production.  If you have questions on this, feel free to leave a comment here.

Enough blabbing, here’s the goods.  WARNING: Long post ahead…but filled with information.

Download Silverlight 4 and tools

To be successful in your evaluation of Silverlight 4 you are going to need some tools.  Here’s the link dump of everything:

These are the full set of tools to help you evaluate Silverlight 4.  At a bare minimum for a developer you’ll need/want Visual Studio 2010 and the Silverlight Tools for VS. 

NOTE: When you install the Silverlight Tools for VS, you get the Windows developer runtime, the Silverlight 4 SDK and the Visual Studio tools/templates.  It is NOT necessary to install the SDK and developer runtimes again if you are using the tools installer.  The developer runtimes are provided for you to put on other developer test machines to help test your applications.  Additionally, RIA Services is also included in the Silverlight Tools for Visual Studio 2010.  If you have a version of RIA Services already installed, you will need to uninstall it.

Go ahead and get the tools starting to download.  In the meantime, here’s some other helpful information for you.

Silverlight 4 Resources

There are a few places for you to go to learn some things:

You should bookmark and subscribe to the above sites for constant updated Silverlight information.

What’s new in Silverlight 4 – feature review

Okay, now on to the details.  Sit back, switch this post to your largest monitor, and grab a drink.  This is a long post intentionally to provide you with details to the framework.  In each area I’ll be sure to point out if there are existing resources (labs, videos, etc.) for that specific feature and be as concise as I can as to be “to the point” about what it provides, what are the requirements and some sample code, where appropriate.  Here we go with the feature dump…


With Visual Studio 2010, we finally have our designer surface back for Silverlight!  Yes, you have an editable design surface for Silverlight…and actually this isn’t just limited to Silverlight 4…it is available for Silverlight 3.  What is great about the Silverlight tools in VS2010 is that the databinding support is pretty rich in the designer surface as well.

DataBinding window in VS2010

Additionally, for WCF RIA Services, we have improved designer/editor support for using DomainSource classes as a Data Source in Visual Studio.  Be sure to grab VS2010 for all your development needs.  VS2010 allows for multi-targeting of Silverlight 3 and 4 applications.

Video: RIA Services Support in Visual Studio 2010

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Printing API

One of the top-most requested features in Silverlight has been to enable some printing support from the Silverlight application client-side versus always having the developer do things server-side.  In Silverlight 4 we’re providing a printing API that we believe to be extensible for the developer and provide you with a simple printing of a visual tree, or a highly extensible model to enable you to create a virtual visual tree to print for the end user directly from Silverlight.

Code sample:

   1: private void PrintAll_Click(object sender, RoutedEventArgs e)
   2: {
   3:     // instantiate a new PrintDocument
   4:     PrintDocument docToPrint = new PrintDocument();
   6:     // set a friendly name for display in print queues
   7:     docToPrint.DocumentName = "Entire Screen Sample";
   9:     // wire up any starting code pre-printing (i.e., UI activity display)
  10:     docToPrint.StartPrint += (s, args) =>
  11:         {
  12:             ActivityDisplay.IsActive = true;
  13:         };
  15:     // tell the API what to print
  16:     docToPrint.PrintPage += (s, args) =>
  17:         {
  18:             args.PageVisual = this.StackOfStuff;
  19:         };
  21:     // wire up any clean-up code pre-printing (i.e., UI activity display)
  22:     docToPrint.EndPrint += (s, args) =>
  23:         {
  24:             ActivityDisplay.IsActive = false;
  25:         };
  27:     // execute the print job
  28:     docToPrint.Print();
  29: }

As you can see above, you can wire up pre- and post-print events for any type of preparation and clean-up code.  The PrintPage is the important area here where the developer would pass a UIElement to print.  This could be something that already exists in the visual tree, or something that is created virtually in-memory and not even added to the visual tree.

Video and Sample Code: Printing API Basics

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Right-click event handling

Do you have an application that has a need for a context-style menu (aka ‘right click’ menus)?  Well, in addition to the MouseLeftButtonUp/Down events, we now enable the MouseRightButtonUp/Down events for you to attach to and handle.  This enables the developer to take control over what you’d like to do when those events occur.  This can be from handling simple commands for gaming (i.e., a right click is a different interaction in the game than the left click) or as well for providing context-style menus for additional functionality within the application.

Sample Code:

   1: public partial class MainPage : UserControl
   2: {
   3:     public MainPage()
   4:     {
   5:         InitializeComponent();
   7:         // wire up the event handlers for the event on a particular UIElement
   8:         ChangingRectangle.MouseRightButtonDown += new MouseButtonEventHandler(RectangleContextDown);
   9:         ChangingRectangle.MouseRightButtonUp += new MouseButtonEventHandler(RectangleContextUp);
  10:     }
  12:     void RectangleContextUp(object sender, MouseButtonEventArgs e)
  13:     {
  14:         // create custom context menu control and show it.
  15:         ColorChangeContextMenu contextMenu = new ColorChangeContextMenu(ChangingRectangle);
  16:         contextMenu.Show(e.GetPosition(LayoutRoot));
  17:     }
  19:     void RectangleContextDown(object sender, MouseButtonEventArgs e)
  20:     {
  21:         // handle the event so the default context menu is hidden
  22:         e.Handled = true;
  23:     }
  24: }

The sample above shows a snippet from implementing a context menu within the application.  The result of the above code looks like this:

right click event sample

As you can see, the event handling is simple and the flexibility exists for you, the developer, to choose what you want to happen functionally and visually when the right-click events occur.

Video and Sample Code: Right-click Mouse Events

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Webcam and micrphone access

Need access to your user’s attached (or integrated) web camera and/or microphone?  You got it.  With a few simple lines of code you can request permission to your users to leverage their capture devices and then capture both the audio and video.

Sample code for requesting permission:

   1: // request user permission and display the capture
   2: if (CaptureDeviceConfiguration.AllowedDeviceAccess || CaptureDeviceConfiguration.RequestDeviceAccess())
   3: {
   4:     _captureSource.Start();
   5: }

Sample code for capturing the video:

   1: if (_captureSource != null)
   2: {
   3:     _captureSource.Stop(); // stop whatever device may be capturing
   5:     // set the devices for the capture source
   6:     _captureSource.VideoCaptureDevice = (VideoCaptureDevice)VideoSources.SelectedItem;
   7:     _captureSource.AudioCaptureDevice = (AudioCaptureDevice)AudioSources.SelectedItem;
   9:     // create the brush
  10:     VideoBrush vidBrush = new VideoBrush();
  11:     vidBrush.SetSource(_captureSource);
  12:     WebcamCapture.Fill = vidBrush; // paint the brush on the rectangle
  14:     // request user permission and display the capture
  15:     if (CaptureDeviceConfiguration.AllowedDeviceAccess || CaptureDeviceConfiguration.RequestDeviceAccess())
  16:     {
  17:         _captureSource.Start();
  18:     }
  19: }

We also provide a very simple API for enabling “snapshot” images from the webcam:

   1: private void TakeSnapshot_Click(object sender, RoutedEventArgs e)
   2: {
   3:     if (_captureSource != null)
   4:     {
   5:         // capture the current frame and add it to our observable collection
   6:         _captureSource.AsyncCaptureImage((snapImage) =>
   7:             {
   8:                 _images.Add(snapImage);
   9:             });
  10:     }
  11: }

I am interested to see how these webcam/microphone features are implemented in the wild by developers!

Video and Sample Code: Webcam and Microphone Support

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Mouse wheel support

In previous versions of Silverlight, you had to rely on some helper classes from either DeepZoom or other sample sites to implement handling the mouse’s scroll wheel functionality on things like ListBox, etc.  We’re now providing APIs for you to handle MouseWheel events.  You can attach this event handler to other items as well (not just ListBox).

Sample Code:

   1: // wire up the event
   2: myRectangle.MouseWheel += new MouseWheelEventHandler(RectangleZoom);
   4: void RectangleZoom(object sender, MouseWheelEventArgs e)
   5: {
   6:     // do something here like alter the scale
   7:     // MouseWheelEventArgs.Delta gives you an int
   8:     // of the amount changed in the scroll event
   9: }

So as you can see, you can easily wire-up the event handler for the MouseWheel event on a particular element and respond accordingly.

Video and Sample Code: Handling MouseWheel Events

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RichTextArea control

One of the requested features has been to provide an editable text control that enabled rich text editing using common rich text changes like bold, italics, different sizes, etc.  Using the RichTextArea, you can now enable these types of editing areas in your application.

Here’s an example of implementing the RichTextArea control:

RichTextArea sample

Video and Sample Code: RichTextArea Control

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ICommand support on ButtonBase and Hyperlink

To help support development patterns like the popular Model-View-ViewModel pattern, support for commanding infrastructures is now provided on ButtonBase and Hyperlink.  These exposed properties, Command and CommandParameter enable binding from a View to a ViewModel approach without the need for click event handlers in code behind files.  This helps aide the pattern of separation of concerns for the UI and code layers.

Sample Code:

   1: <UserControl.Resources> 
   2:     <local:ProductViewModel x:Key="ViewModelContext"/> 
   3: </UserControl.Resources> 
   4: <Grid DataContext="{StaticResource ViewModelContext}" Name="LayoutRoot"> 
   5: <TextBox x:Name="CostThresholdFilter"/> 
   6: <Button Content="Load Products" Width="120"  
   7:     Command="{Binding FindMatchingProducts}"  
   8:     CommandParameter="{Binding Path=Text, ElementName=CostThresholdFilter}"/>

In this example above, the XAML binds the Button to an event, FindMatchingProducts, from the DataContext (the “ViewModelContext” resource) as well as providing the parameter, CostThresholdFilter, from another UIElement on the page.  For those implementing solutions using the MVVM pattern (or other similar patterns), this added support for ICommand is a welcome addition!  Get those MVVM framework revisions working :-).

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Clipboard API

Prior to now, having a reliable method for providing contents that can be temporarily held in the machine’s “clipboard” memory area involved an IE-only solution or introducing other platforms into your Silverlight application.

With the addition of the Clipboard API, you can now have a cross-platform mechanism in Silverlight to provide this facility for you.

Sample Code:

   1: Clipboard.SetText("Some text to save in the clipboard area");

This sample above shows setting some simple text to the Clipboard which could then be pasted to the Silverlight application, or to other applications the user is using as this is now in the machine’s clipboard memory.

Video and Sample Code: Accessing the Global Clipboard Programmatically

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Host HTML content using WebBrowser control

When you are working in the web world, you likely are dealing with HTML content in some area.  Especially if you are creating content-managed systems, sometimes that content is stored as HTML.  Enabling hosting HTML content in Silverlight is now possible by providing a simple WebBrowser control that will enable you to provide string-based HTML contents or navigate to a fully interactive URL.

Sample Code (XAML):

   1: <WebBrowser x:Name="MyBrowserControl" Width="800" Height="600" />

Sample Code (C#):

   1: MyBrowserControl.NavigateToString("<div style='color:red;width:100;height:100'><b>Tim Heuer</b></div>");

As an example, here’s a Silverlight application hosting an embedded YouTube Flash video:

Hosting HTML YouTube video in Silverlight

Hopefully this will be helpful in developing your Silverlight applications.  Additionally, you can also use the HtmlBrush to fill elements using HTML content.

Video and Sample Code: Hosting HTML Content in Silverlight

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Elevated trust applications

One thing users have been asking for is to enable Silverlight out-of-browser (OOB) applications to have more privileges.  You can now alter the OOB manifest to request more elevated permissions for your application.  Using Visual Studio you can look at the project properties and enable the checkbox to add this request:

Elevated trust manifest setting

The result is that the OOB install dialog now looks a little different and warns the user of these elevated privileges:

Trusted application install prompt

See the next sections for things that you can do in OOB mode now while in a trusted application (aka elevated mode).  It is important to note that this trusted application request still does not involve installing any additional runtime for the user…it is a part of the Silverlight 4 runtime – no additional download/framework would be required.

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Access local files on user’s machine

In order to read/write data to the user’s machine, you normally have to do it through a mechanism like OpenFileDialog (read) and SaveFileDialog (write).  In Silverlight 4 you can now have direct local file access to the users’ "My” folders in their profile.  These are things like MyDocuments, MyVideos, MyMusic, etc.  On OSX platform these map to the same user-level profile folders like /users/timheuer/Videos. 

You use the Environment namespace to get the path locations for the operation you are wishing to do.

Sample Code:

   1: private void EnumerateFiles(object sender, RoutedEventArgs e)
   2: {
   3:     // create a collection to hold the file enumeration
   4:     List<string> videosInFolder = new List<string>();
   6:     // using the file api to enumerate
   7:     // use the SpecialFolder API to get the users low trust "My Document" type folders
   8:     var videos = Directory.EnumerateFiles(Environment.GetFolderPath(Environment.SpecialFolder.MyVideos));
  10:     // enumerate the folder
  11:     foreach (var item in videos)
  12:     {
  13:         videosInFolder.Add(item);
  14:     }
  16:     // bind the data
  17:     VideoFileListing.ItemsSource = videosInFolder;
  18: }

This feature requires a trusted application (elevated permissions).

Video and Sample Code: Local File Access

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COM interoperability

Have you had the need to interoperate with device peripherals that only expose a COM interface?  What about having your Silverlight application talk with Office applications?  Using the ComAutomationFactory API, you can now have your Silverlight application instantiate and interact with COM applications on the Windows client.

Sample Code (interacting with Excel):

   1: // create an instance of excel
   2: dynamic excel = ComAutomationFactory.CreateObject("Excel.Application");
   4: excel.Visible = true;  // make it visible to the user.
   6: // add a workbook to the instance 
   7: dynamic workbook = excel.workbooks;
   8: workbook.Add();
  10: dynamic sheet = excel.ActiveSheet; // get the active sheet

This feature requires a trusted application (elevated permissions).  Notice that this is done via the dynamic keyword in C# 4.0.  One thing to also note that in the tooling you will not get IntelliSense support for your COM created objects.  Keep that documentation for that API handy!

Video and Sample Code: COM Object Access in Trusted Applications

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Notification (aka “toast”) API

Ever want your application to provide a notification mechanism to the user?  This is often referred to as “toast” where a subtle notification temporarily displays in the user’s screen providing some information provided by the application.  Perhaps one of the more common uses of this is in mail applications, like Outlook, where new mail notifications pop-up message notification windows near the system tray in Windows.

By using the NotificationWindow in Silverlight, you can provide a simple or customized notification mechanism for your application.

Sample Code:

   1: private void CustomNotificationButton_Click(object sender, RoutedEventArgs e)
   2: {
   3:     // create the nofitication window API
   4:     NotificationWindow notify = new NotificationWindow();
   5:     notify.Height = 74;
   6:     notify.Width = 329;
   8:     // creating the content to be in the window
   9:     CustomNotification custom = new CustomNotification();
  10:     custom.Header = "Sample Header";
  11:     custom.Text = "Hey this is a better looking notification!";
  12:     custom.Width = notify.Width;
  13:     custom.Height = notify.Height;
  15:     // set the window content
  16:     notify.Content = custom;
  18:     // displaying the notification
  19:     notify.Show(4000);
  20: }

Here’s an example of a styled NotificationWindow content:

Sample NotificationWindow

Notifications can only be done in Silverlight out-of-browser applications, and are simple to implement in few lines of code.

Video and Sample Code: Notification Window API

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Network authentication in web requests

At times, you may be interacting with 3rd party (or perhaps your own) services that require authentication information to be passed into the service call.  This authentication information may be different than the logged-on user’s current information.

We have enabled providing NetworkCredential information via the ClientHttp networking stack that was introduced in Silverlight 3.  For example, to pass a username/password (basic auth) to a service call using this method would be something like this:

   1: // NetworkCredential passing is available in ClientHttp networking stack
   2: WebRequest.RegisterPrefix("http://", System.Net.Browser.WebRequestCreator.ClientHttp);
   4: WebClient myService = new WebClient();
   5: myService.Credentials = new NetworkCredential("someusername", "somepassword");
   6: myService.UseDefaultCredentials = false; // must be set to false if providing your own credentials
   7: myService.DownloadStringCompleted += new DownloadStringCompletedEventHandler(OnResultCompleted);
   8: myService.DownloadStringAsync(new Uri(http://somewebsite.com/authenticatedservice));

Note that we first register the prefix to use the ClientHttp networking stack.  The second thing to note is that in WebClient, you still must specify UseDefaultCredentials=”false” even though you are providing new credentials.  If you don’t, the default credentials will still be used.

Video and Sample Code: Network Authentication in Web Requests

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Cross-domain Networking changes

One of the more significant changes to cross-domain networking comes when you have a trusted application.  For services that have a closed cross-domain policy file (via clientaccesspolicy.xml or crossdomain.xml), if your application is a trusted application (elevated permissions), then the requirement for a cross-domain policy file is no longer required.

This only applies to trusted applications.

Video and Sample Code: Network Cross-domain Request in Trusted Application

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Full keyboard access in full screen

If you are developing kiosk applications or other Silverlight applications that run in full-screen mode (IsFullScreen=”true”), you have noticed that only a limited set of keyboard input was enabled.  In Silverlight 4 trusted applications, any application in full-screen mode can have full keyboard input for things like TextBox or other input controls.

This only applies to trusted applications.

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The TextBlock control has a new property called TextTrimming that enables you to use the WordElipse trimming value.  When the property is set, any text exceeding the visible limit of the control will be truncated and an ellipsis will be displayed to the user indicating more content.

Sample Code:

   1: <TextBlock HorizontalAlignment="Left" VerticalAlignment="Top" 
   2:     Text="The quick brown fox jumped over the tall white fence"  
   3:     TextTrimming="WordEllipsis" Width="120" />

Sample Output:

TextTrimming output sample

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ViewBox control

As items in the Silverlight Toolkit mature in the codebase, these controls move into the core for Silverlight.  In this release, ViewBox has reached that level and is now provided in the core.  A ViewBox is a container control that aims to help constrain the contents of the ViewBox to a specific size or area and automatically handle scaling, etc.

Video and Sample Code: Using the ViewBox Control

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Bi-directional and complext text, Right-to-left support in controls

If you are writing an application that requires right-to-left (RTL) support in either text and/or controls, a new attribute for UIElement is now provided for you.  The FlowDirection attribute can be applied to represent the element in RTL format. 

Sample Code:

   1: <StackPanel HorizontalAlignment="Center" VerticalAlignment="Center" x:Name="ControlSamples">
   2:     <TextBlock FlowDirection="LeftToRight" Foreground="White" Text="BiDi and RTL Sample" FontSize="20" Margin="20" />
   3:     <RichTextArea TextWrapping="Wrap" Width="600" Height="150"></RichTextArea>
   4:     <TextBlock FontSize="24" Foreground="White" Text="قفز الثعلب البني السريع فوق الكلب الكسول." />
   5:     <ListBox>
   6:         <ListBox.Items>
   7:             <ListBoxItem Content="قفز الثعلب البني السريع فوق الكلب الكسول." />
   8:             <ListBoxItem Content="Option 1" />
   9:             <ListBoxItem Content="Option 2" />
  10:             <ListBoxItem Content="Option 3" />
  11:             <ListBoxItem Content="Option 4" />
  12:         </ListBox.Items>
  13:     </ListBox>
  14: </StackPanel>

This can be applied to a higher level in the visual tree and gets automatically applied to child levels.

Video and Sample Code: BiDi and Right-to-left Support

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Offline DRM for media playback

The next major wave of PlayReady innovation being built into Silverlight focuses on meeting the top media customer ask for the Silverlight DRM client – support for Offline scenarios.  The three key business models targeted for this release of the Silverlight DRM client are Rental, Subscription, and Purchase.  The Silverlight PlayReady ecosystem has several features that are valuable for these business models.

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H.264 protected content via PlayReady

PlayReady content protection for Silverlight and VC-1 encoded media has already proven to be a reliable and seamless experience to the user.  With Silverlight 4, this content protection is extended to H.264 encoded media assets.

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Using Silverlight application as a drop target from your desktop

For some scenarios, you may have wanted to be able to drag a file from your desktop or file explorer on to your Silverlight application.  By enabling the AllowDrop attribute on UIElement in this release, you can now accommodate those scenarios.

Sample Code:

   1: public MainPage()
   2: {
   3:     InitializeComponent();
   4:     Loaded += new RoutedEventHandler(MainPage_Loaded);
   6:     // wire up the various Drop events
   7:     InstallButton.Drop += new DragEventHandler(InstallButton_Drop);
   8:     InstallButton.DragOver += new DragEventHandler(InstallButton_DragOver);
   9:     InstallButton.DragEnter += new DragEventHandler(InstallButton_DragEnter);
  10:     InstallButton.DragLeave += new DragEventHandler(InstallButton_DragLeave);
  11: }
  14: void InstallButton_Drop(object sender, DragEventArgs e)
  15: {
  16:     IDataObject foo = e.Data; // do something with data
  17: }

This will be most helpful in file upload applications.

Video and Sample Code: Using Silverlight as a Drop Target

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IDataErrorInfo and asynchronous validation

Silverlight adds the IDataErrorInfo interface enables the reporting of validation errors that a user interface can bind to.  When an entity implements this interface and the entity is involved in a binding operation, it invokes the indexer to validate the properties.  The bound target properties in the UI will receive the error messages and display the validation states if the ValidatesOnDataErrors property is set to true.

IDataErrorInfo is limited to validating on a per property basis. However, Silverlight 4 also adds the INotifyDataErrorInfo interface that allows validation across properties of an entity. It also allows entity objects to enable notification of data errors in the UI. INotifyDataErrorInfo allows developers to provide custom, asynchronous validation support to access server-side validation logic.  It exposes a HasErrors property to indicate if there are any errors and has a GetErrors method to retrieve the errors.  The ErrorsChanged event is raised when new errors are added. If the binding property ValidatesOnNotifyDataErrors is set to true and the source object implements the interface, the binding engine in Silverlight will listen for the ErrorsChanged event.

Video and Sample Code: Data Validation

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DependencyObject Binding

Silverlight introduces the ability to bind properties on a DependencyObject (DO) and not just on FrameworkElements.  For example, in Silverlight you can bind the rotation angle of a RotateTransform to a Slider control.

Sample Code:

   1: <Rectangle Width="100" Height="100"  
   2:         RenderTransformOrigin="0.5, 0.5" Background="#FF2B6092"> 
   3:     <Rectangle .RenderTransform> 
   4:         <RotateTransform Angle="{Binding ElementName=slider, Path=Value}" /> 
   5:     </Rectangle .RenderTransform> 
   6: </Rectangle > 
   7: <Slider x:Name="slider" Height="20" Margin="0,225,0,55" Minimum="0"  
   8:         Maximum="360" />

This is a highly requested data binding enhancement that should be useful to designers and developers.

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StringFormat, TargetNullValue, FallbackValue

If you’ve ever done databinding in XAML using simple things like currency, dates, etc. then you have likely created a ValueConverter.  While for simple things it is not difficult, it was often a tedious and repetitive task.

StringFormat is now available to you for a simpler solution for XAML databinding and formatting the output.

Sample Code:

   1: <TextBox Text="{Binding Path=PublishedDate, Mode=OneWay, StringFormat='MM-dd-yyyy'}"/>

Additionally, you can also specify Fallback and TargetNull values in your binding syntax:

   1: <TextBox Text="{Binding Path=SomeBindingValue, Mode=TwoWay, FallbackValue=N/A}" /> 
   2: <TextBox Text="{Binding Path=QuantityOnHand, Mode=TwoWay, TargetNullValue=0}" />

The FallbackValue displays a value when the binding operation is unsuccessful, where the TargetNullValue helps provide a value when the result of the binding value is NULL.

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Managed Extensibility Framework (MEF)

This release of Silverlight 4 brings support for the Managed Extensibility Framework (MEF) in the SDK.  This is far to important of a topic (and too broad of a topic) to cover in a simple paragraph.  Take a look at Glenn Block’s session at PDC (when available) for an in-depth look at this support for MEF in Silverlight.

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DataGrid enhancements

DataGrid is a commonly used control for building line-of-business applications.  Over time, the DataGrid has continually undergone improvement and this release is no different.  Take a look at the video for the improvements in the DataGrid control.

Video and Sample Code: DataGrid Improvements

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Fluid user interface support

In order to support more fluid user interface experiences, new states have been added to ItemsControl.  These new states: BeforeLoaded, Loaded and Unloaded help animate the transition of contents between states in an ItemsControl and provide a more interactive and “fluid” experience to the user.

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Implicit theming for controls

Silverlight 4 introduces new styling features that allow you to create a style as a resource that can be used implicitly by all elements of a target type. This allows application developers to customize the look across multiple instances of a control and modify the appearance of these control instances by changing the implicit style.

Sample Code:

   1: <UserControl.Resources>
   2:     <Style TargetType="Button">
   3:         <Setter Property="Foreground" Value="Red" />
   4:         <Setter Property="FontSize" Value="24" />
   5:     </Style>
   6: </UserControl.Resources>

Would result in any <Button> element having a FontSize of 24 and red foreground text.

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Google Chrome support

As browser markets evolve, so must we.  During this release cycle we will be officially providing support for the Google Chrome browser.  To date, Silverlight has generally worked in Chrome, but we’ll be adding Chrome to our official test/support matrix with this release.  We’ve had a working communication group with Chrome to ensure that any questions we’ve had to make sure Silverlight runs well within Chrome are answered.

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Summary and Feedback

So there you have it.  Some new toys to play around with.  What do you think?  Please be sure that if you find any issues or compatibility with existing compiled Silverlight applications that you report them in the forum for Silverlight 4 beta.

There are a few other items in the build, so be sure to read the Silverlight 4 Beta information as well as the what’s new documentation and breaking changes documentation provided.

I’m very excited about this release and hope you are as well.  I can’t wait to see what you guys and gals do with these new features!