The Windows 7 Shell populates and manages the Recent and Frequent destination

The Windows 7 Shell populates and manages the Recent and Frequent destination categories. Simple mechanisms govern the definition of what a recent or frequent item might be and performing integration tasks with these mechanisms does not require any interaction with taskbar-specific APIs.

If your application has a well-defined file type, your application’s installer should register this file type to associate it with your application. This association is recorded in the Windows 7 registry, under the HKEY_CLASSES_ROOT registry hive. Even if your application is not the primary handler for the file type (for example, Microsoft Visual Studio can open XML documents, but it’s not necessarily the primary handler for .xml files), you should still associate it with file types that it can open.

Associating Your Application with a File Type

To associate your application with a file type, you need to fill the registry entries under the HKEY_CLASSES_ROOT registry hive. Specifically, you need to create a key with your file extension (for example, .xml) and a subkey called OpenWithProgIds. Within the subkey, create a string value with your ProgID in the standard ProgID format (for example, VisualStudio.9.0).

Note The following MSDN page offers a detailed walkthrough of this process: http://msdn.microsoft.com/en-us/library/cc144148(VS.85).aspx. Additionally, you might find useful the Windows 77.DesktopIntegration.RegistrationHelper utility, which performs the necessary steps to register a file type association in the Windows 7 registry. (The utility is available as part of the Windows 7 7 Taskbar Sample Library.)

Next, create another key under the HKEY_CLASSES_ROOT registry hive with the name of the ProgID used in the previous steps. Under that key, add subkeys to form the following path: shell\Open\Command. Within the Command subkey, add a default string value with the full path to your executable and additional command-line parameters if desired. Within the command-line string, you can use the %1 placeholder, which the Windows 7 Shell replaces with the name of the document being opened. The following screen shot is an example of a registry association for the .ascx file extension with the Visual Studio ProgID.

If you successfully followed these steps, the Windows 7 Shell recognizes your application as a handler for the specified file type. Successful completion of these steps enables users to launch your application by double-clicking items with your file extension in Windows 7 Explorer, and it enables you to embed destinations in your application’s Jump List.

The Windows 7 Shell adds items to the Recent and Frequent lists for your application when one of the following actions occurs:

• The item is used to launch your application directly for example, when you double-click a file or a shortcut in Windows 7 Explorer.
• The item is selected by a user in a common file dialog (Open or Save).
• The item is passed as a parameter to the SHAddToRecentDocs function, which is part of the Windows 7 Shell API.

Note Common file dialogs provide a standard look and feel as well as additional functionality to Open and Save operations throughout the Windows 7 Shell. Applications that use the common file dialogs will always benefit from the latest version of the user interface provided by the underlying operating system (regardless of the version of Windows 7 they were compiled on). Taking advantage of Windows 7 Shell Libraries and of Recent and Frequent categories is greatly simplified if you use common file dialogs in your application. For more information about common file dialogs, consult the MSDN documentation.

The first two actions do not require any interaction on your application’s behalf the Windows 7 Shell automatically maintains the Recent and Frequent item lists for your application. Therefore, if your Jump List contains the Recent or Frequent destination category and your application is registered as a handler for some file type, the application’s Jump List automatically contains recently or frequently accessed items. If you choose to notify the Windows 7 Shell directly, you can use the SHAddToRecentDocs Win32 API or the managed equivalent the JumpList.AddToRecent method which is part of the Windows 7 API Code Pack. This has the same effect as populating the Jump List with the recently or frequently accessed items.

The only thing left to do, then, is to let the taskbar know that your application requires a Jump List with one of the system destination categories Recent or Frequent. Remember that to display the Jump List correctly and associate it with the appropriate taskbar button, you need to set the window application ID (or the process application ID) to the same consistent value you use throughout your application.

If you decide to use the Recent destination category, you don’t need to do anything else to get the Jump List to work. However, if you want to use the Frequent destination category, you need to follow through with a list-building transaction. The following code sample, which displays both the native and managed APIs, shows how to create a Jump List for an application, add to it the Frequent destination category, and ensure that it’s populated with one recently used item:

//C++:
   ICustomDestinationList* pJumpList = NULL;
   if (FAILED(CoCreateInstance(
   CLSID_DestinationList, NULL, CLSCTX_INPROC_SERVER, IID_PPV_ARGS(&pJumpList))))
   goto Cleanup;
   if (FAILED(pJumpList->SetAppID(L"Microsoft.Samples.MyApplication")))
   goto Cleanup;
   UINT uMaxSlots;
   IObjectArray* pRemoved;
   if (FAILED(pJumpList->BeginList(&uMaxSlots, IID_PPV_ARGS(&pRemoved))))
   goto Cleanup;
   if (FAILED(pJumpList->AppendKnownCategory(KDC_FREQUENT)))
   goto Cleanup;
   if (FAILED(pJumpList->CommitList()))
   goto Cleanup;
   Cleanup:
   if (pJumpList != NULL)
 pJumpList->Release();
//C#:
 JumpList jumpList = JumpList.CreateJumpList();
 jumpList.KnownCategoryToDisplay = JumpListKnownCategoryType.Frequent;
 jumpList.AddToRecent("MyFile.ext");
 jumpList.Refresh();

After completing these steps, your application will have a Jump List with the Recent or Frequent category enabled. If your users are using Windows 7 Explorer to launch your application from individual items, and if you’re using the common file dialogs for Open and Save functionality, there’s nothing else you need to do to manage the Recent and Frequent categories.

It usually doesn’t make sense to include both the Recent and Frequent categories in the same Jump List. It is recommended that you choose one or the other.