An update that extends the mechanism for displaying snap-in context Help topics is available for the MMC in Windows Server 2008

Pre-update behavior

The section describes Help event behavior before the update is applied. The snap-in defines the HelpTopic path, and the MMC caches this information. When the MMC displays a context Help topic, the MMC opens a standard MMC Help window without calling the snap-in. If the snap-in has defined the Help topic for the selected item, the MMC Help window shows that topic. If no Help topic is defined, the MMC Help window shows the default MMC 3.0 Help topic.

A snap-in can set the HelpTopic property in the following three locations:

• The ScopeNode class
• The PropertyPage class
• The SelectionData property that is used by the View class

Post-update behavior

After the update is applied, developers have two mechanisms for displaying a Help topic including the one that exists before the update is applied.

Callback

A snap-in sets the UseCustomHelp property of the SnapInSettingsAttribute class to True, and then the snap-in registers a snap-in level callback. The callback is triggered by the MMC when the snap-in requests that MMC display a Help topic. When the UseCustomHelp property is set to True, the pre-update mechanism is ignored. The MMC does not display the standard MMC Help window.

HelpTopic property

This mechanism is the one that existed before the update was applied. This mechanism works only if the snap-in does not set the UseCustomHelp property to True.

To display the Help topic in a customized way, the MMC must follow these steps:

1. It must set the UseCustomHelp property of the SnapInSettingsAttribute class to True.
2. It must register a callback with MMC.

When the MMC receives a request to display a Help topic, the MMC first checks the snap-in registration information to see whether the snap-in has set the UseCustomHelp property. If the snap-in has not set the UseCustomHelp property to True, the MMC starts a standard MMC Help window. If the snap-in has set the UseCustomHelp property to True, the MMC does not start a standard MMC Help window. Instead, the MMC finds and triggers the callback that is registered by the snap-in. In this case, the snap-in is completely responsible for displaying the Help topic. If the snap-in wants to use the callback mechanism to show a standard MMC Help window, it can call the SnapInBase.ShowHelpTopic function.

New APIs that are exposed to snap-ins

UseCustomHelp is a new property that is added to the SnapInSettingsAttribute class. By default, this property is set to False. To customize the MMC Help display, a snap-in should set this property to True.

Microsoft.ManagementConsole.SnapInCallbackService is a new class that lets a snap-in register a snap-in level callback. The callback will handle the Help topic display.

SnapInHelpTopicCallback is a type of delegate that a snap-in should create and register with the MMC. This delegate takes an object as a parameter to specify the item on which the Help topic is requested. This parameter can be one of the following types of objects that have the HelpTopic property:

• ScopeNode
• SelectionData
• PropertyPage

This parameter can also be Null. A Null parameter indicates that the MMC is unable to find an object.

RegisterSnapInHelpTopicHandler is a function that a snap-in calls to register a callback. This function takes the following two parameters:

• Snap-in instance
• Callback function
  

Neither of the parameters can be Null. Otherwise, the MMC throws an ArgumentNullException exception.

Update information

The following files are available for download from the Microsoft Download Center:

Update for Windows Server 2008 x64 Edition
Download the KB951725 package now.

Update for Windows Server 2008 for Itanium-based Systems
Download the KB951725 package now.

Update for Windows Server 2008
Download the KB951725 package now.

Update for Windows Vista
Download the KB951725 package now.

Update for Windows Vista for x64-based Systems
Download the KB951725 package now.

For more information about how to download Microsoft support files, click the following article number to view the article in the Microsoft Knowledge Base:

119591 How to obtain Microsoft support files from online services

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A supported hotfix is available from Microsoft. However, this hotfix is intended to correct only the problem that is described in this article. Apply this hotfix only to systems that are experiencing this specific problem. This hotfix might receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next software update that contains this hotfix.

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Prerequisites

No prerequisites are required.

Restart requirement

You do not have to restart the computer after you apply this update.

Update replacement information

This update does not replace any other updates.

File information

The English version of this update has the file attributes (or later file attributes) that are listed in the following table. The dates and times for these files are listed in Coordinated Universal Time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time item in Control Panel.

Windows Server 2008, 32-bit editions

Windows Server 2008, Itanium-based editions

Windows Server 2008, 64-bit editions