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MMCPropertyHelp callback function

The MMCPropertyHelp function is introduced in MMC 1.1.

The MMCPropertyHelp function displays the specified HTML Help topic in the merged MMC HTML Help file for a property page.


HRESULT MMCPropertyHelp(



A pointer to a NULL-terminated string specifying the topic to display in the merged MMC HTML Help file. The string must have the following format:


where helpfilename is the file name of the snap-in's HTML Help file (.chm) that MMC merged into the MMC HTML Help file (file name only, not the path to the original HTML Help file) and topicfilename is the internal path to the topic file within the snap-in's .chm file. The author of the snap-in's HTML Help file determines whether there is an internal directory structure for the topic HTML files or if all topic HTML files are at the root of the .chm file.

For example, if the snap-in had the HTML Help file mysnapin.chm merged into the MMC HTML Help file and a topic HTML file that had the internal Help file path of htm/snphlp01.htm, the string would have the following form:


Support for numeric IDs for topics is not available in this release.

Return value

This callback function can return one of these values.


The specified HTML Help topic was successfully called.


Call MMCPropertyHelp in the notification handler for the MMCN_CONTEXTHELP notification.

A snap-in can provide context help on a property page. Because an MMC property sheet is typically running on a separate thread, the property page cannot use the IDisplayHelp interface directly. Instead, the property page can call MMCPropertyHelp from the MMC library to achieve the same result. MMCPropertyHelp takes the same topic string parameter as IDisplayHelp::ShowTopic and handles marshaling the request to the main MMC thread.

If the snap-in handles the MMCN_CONTEXTHELP notification, MMC expects the snap-in to specify a Help topic for the selected item. Consequently, in the notification handler for the MMCN_CONTEXTHELP notification, the snap-in has two options:

  • It can call IDisplayHelp::ShowTopic or MMCPropertyHelp to specify the Help topic and then return S_OK to indicate success. Be aware that the snap-in should only return S_OK if it specifies a Help topic. If the snap-in returns S_OK without specifying a Help topic, no Help topic will be displayed.
  • It can return S_FALSE to the notification. MMC then brings up the table of contents with the default MMC topic selected.


Minimum supported client

Windows Vista

Minimum supported server

Windows Server 2008



See also