Welcome to yet another Windows 7 Taskbar post. In the previous post, Developing for the Windows 7 Taskbar – Get to Know Your Application ID , we introduced a very important component of the underlying architecture of the Taskbar, the Application ID (AppID), which is the key controller of how different applications are grouped under the same Taskbar button. The AppID also has a direct affect on how Jump List items are aggregated and populated in the Jump List.
Microsoft designed the Windows 7 Taskbar to provide users with quick and easy access to those “things” they use most frequently. “Things” can be any type of content such as pictures, music, word documents or links and shortcuts to applications or folders, or any other type of “clickable” item in Windows. By quick and easy access, we mean the ability to access commonly used programs with a single mouse click or with a significantly reduced number of clicks per operation. Quick and easy access also means users should be able to “jump” directly to those things they want to work with and start working with them in a single mouse click. To provide this functionality, the Windows 7 Taskbar introduces the concept of “Jump Lists.” More info about the reasons and background for creating the Taskbar Jump List can be found in Chaitanya’s Engineering Windows 7: The Windows 7 Taskbar post, and Windows 7 New Taskbar - An Overview video on Channel 9.
As much as I love talking about the reasons for creating the new Taskbar (since I love user functionality and usability in general) I am going to focus on the API for using the Taskbar. As a developer, you should think of a Jump List as your application's own mini Start Menu. Jump Lists bring to the surface commonly used destinations (nouns) and tasks (verbs) of a program. This enables easy user access to destinations by eliminating the need to launch the application and then load the relevant content, or by performing common tasks without launching the application in advance. The following picture illustrates how Jump Lists work with Microsoft Office Word 2007. You can see that under the “Recent” category, there is a list of recent documents that I’ve used with Office Word. Clicking on one of the items in the “Recent” list will launch Office Word with the relevant document already loaded.
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We previously identified Word 2007 as an example of an application that “plays” nicely with the Windows 7 Taskbar even if that application was released a long time before the Windows 7 Taskbar was available. The Taskbar buttons are all grouped under the same Taskbar icon and the Jump list is automatically populated with the most recently used Word documents. In the next post, I will explain in detail how Jump List are populated automatically like Office Word 2007 and word documents. For this post, let’s focus on the different Jump Lists players.
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The default Out-of-The-Box tasks that are shipped provide the means to launch a new instance of the application, to pin or unpin an application to the taskbar, and to close the application. You can access the Jump List by right clicking on an application icon in the Taskbar. However, as the following picture illustrates, you can opt to take more control of the Taskbar experience by customizing the context of the Jump List for your application.
Definitions from the Windows 7 SDK:
”… Destinations are items that appear in the Recent, Frequent, or custom categories (the 'Important' category in the diagram above), based on the user’s item usage. Destinations can be files, folders, Web sites, or other content-based items, but are not necessarily file-backed. Destinations can be pinned to or removed from the Jump List by the user. They are generally represented by IShellItem objects, but they can also be IShellLink objects…”
”…Tasks are common actions performed in applications that apply to all users of the application regardless of the individual usage patterns. Task can’t be pinned or removed. Tasks are represented by IShellLink objects because they are actually links (with parameters – optional) to commands – 'Actions'…”
As developer, you can:
- Control Application Destinations (that is control the items you want users to be able to “Jump” directly into and start working on)
- Destinations can be any one of the known categories such as Recent or Frequent.
- The Custom category is just like any other Destination category, except that it allows you to create a new name for that category as well as populate it with items of your choice.
- The Pinned category is provided for pinned items that users want to keep permanently in their Jump Lists. Please note: ONLY users can pin items in the Jump List, there is NO supported programmatic way that you, as developer, can pin an item.
- You can completely remove the Pinned category from the Jump List so the user cannot pin items – but you might want to think twice before preventing users from pinning items in your application.
- Define Common User Tasks
- The Taskbar surfaces its own out-of-the-box tasks such as launching, pinning/unpinning, or closing the application. As developers we have no control over the Taskbar Tasks. However, we do control the User Tasks.
- User Tasks are common tasks the application developer wants to surface at the Jump List level that will enable users to perform a task directly from the Jump List (for example, Play all music in media player without switching to media player). Usually, this will result in launching an instance of the application and performing the task, or launching another application, like Internet Explorer, when clicking on the “Go to MSN Home Page” task in the Windows Live Messenger Jump List as shown in the next picture. Again, all of the above Jump List functionality saves time and reduces the number of clicks needed to achieve the user's end goal, thereby making the user happy.
In the next post, we will dive into the Taskbar Jump List API. But first, we need to address the Taskbar programming model. The Taskbar exposes its set of APIs like any other Windows Shell component, through a set of COM interfaces. However, there are a few actions we developers can do even before starting to use the Windows Taskbar COM APIs.