With the importance of information on the Internet and on intranets growing every day, users need fast, simple ways to get to data. Before Internet Explorer 4.0, users had to start a separate application to interact with Web content, and all Web content was displayed in a different, highly constrained application window.

The desktop has traditionally been a primary home base for users—a place to store documents and applications for easy and fast access. At the same time, users have enjoyed only limited customization of their desktops. With Internet Explorer 4.0, Microsoft has greatly enhanced users’ ability to store any information on the desktop and keep it updated automatically. The result is the Active Desktop.

Key Features of the Active Desktop

• Pictures of sports highlights or breaking news stories, automatically updated from the Web every day
• A Web site displayed right on the desktop as a moveable, resizable floating frame
• Tickers for sports scores, stock quotes, or weather reports
• Headline lists for news stories or announcements
• Popup messages for internal corporate announcements
• Notifications for new mail, chat, or public discussion forums

• Supports roaming use and lockdown (Beta 2): Network administrators can create custom HTML-based desktops for their users so that a customized work environment can be created for people with different job functions.

What are the Benefits of the Active Desktop?

• Personalized user interface. It’s fast and easy to add components to the Active Desktop. All you have to do is point it towards the objects you’re interested in, and then you’ve got a desktop built specifically for you, providing you with the information you need.
  
  
• Reduced support costs. Corporate IT departments can create standard HTML-based desktops for their end users, with links to important Web pages, e-mail aliases, documents, or applications, and then lock it down. By simplifying the user interface to a standard set of Web pages, the burden on the Help desk is reduced. Internet Explorer 4.0 even enables administrators to turn off the default set of icons on the desktop, providing even more control of the desktop for IT managers.

How does the Active Desktop work?

The Active Desktop is made up of two layers: an HTML background and an icon layer that sits atop the HTML background. The icon layer supports all of the features of the single Explorer, such as single click navigation and the other features discussed earlier. Integrating an HTML background layer onto the desktop means that the desktop understands HTML and all of the associated software components such as ActiveX, Java, and ActiveX scripting. In fact, there is an ActiveX control that manages all of the positioning of the desktop components, allowing users to move and resize them simply by using drag and drop, as well as layering components on top of each other.

Desktop components are typically designed to provide short capsule or summary information in a small amount of screen space. It makes sense for desktop components to offer hyperlinks or hotspots so the user can click a designated area, and then quickly open a new browser to get the details they need.

The desktop HTML layer is described by a single, local HTML file that is created and edited automatically by Internet Explorer 4.0. This HTML file contains the following:

• HTML tags that represent each desktop component. Each desktop component consists of a single HTML tag with an arbitrary x and y position (see Dynamic HTML earlier in this document for a description of 2D positioning and layering). The HTML tag for a desktop component can either be an image (<IMG>) tag or a floating frame (<IFRAME>) tag, and is generated automatically by Internet Explorer 4.0. The floating frame is the most commonly used approach, since it neatly encapsulates an entire arbitrary HTML document that can contain anything the publisher desires. In either case, there is a single URL that points to the actual content.
  
  
• An ActiveX control that enables moving and resizing and helps manage the list of desktop components.
  
  
• Any other static HTML that the user wants to have in the background. By default, this is just a reference to the user's chosen wallpaper, which is exposed as the background watermark for the HTML page.

Adding and Updating Components

Internet Explorer 4.0 allows users to add desktop components in two ways:

• "Designed for Internet Explorer 4.0" desktop components. If a publisher has created a desktop component following the instructions on http://www.microsoft.com, they can publish their component on their Web site. Microsoft has authored an ActiveX control to assist in setting the default configuration and scheduling options; the user simply clicks the control to install the component.
  
  
• Other desktop components. Users can choose any picture or Web site to be a component on their desktop. The Display icon in the Control panel contains a new tab labeled Desktop that allows a user to enter an Internet address and create an image or floating frame directly on their desktop.

Works Offline

To keep all information up-to-date, all desktop components are added automatically to the user's Internet Explorer 4.0 Subscriptions folder. This has three effects:

• All content is automatically cached offline and marked as "sticky" in the cache, so its content is available even if no Internet connection is available.
  
  
• Users will be automatically notified whenever the component is changed on the server. Internet Explorer 4.0 provides this service automatically for all subscriptions.
  
  
• Each desktop component can be scheduled individually for updates on the client. For example, a user could have a sports ticker that gets updated once an hour, a news headline service that gets updated once a day, and a comic strip that gets updated once a week, all sharing space on the same desktop. Internet Explorer 4.0 automatically refreshes the associated HTML content on the desktop whenever the update occurs.

Since each desktop component is simply defined by an address, any content that the component references can synchronize with its corresponding content on its original server. For more details, see the Subscriptions section of this document.

Drag and Drop Customization

Note that any desktop component can be moved or resized by the user. To make this feature intuitive to users, the move and resize features become available as soon as the user moves the cursor over a component.

To move a component, the user positions the cursor anywhere over it. The ActiveX control mentioned earlier that has automatically been added to the desktop HTML document will detect the mouse motion and create a small move handle in the upper-left hand corner of the component. The user can then drag this handle around the screen to reposition the component.

Resizing works similarly. To resize a component, the user positions the pointer over any edge of the rectangular 2D HTML layer that contains the component. The cursor will then change to a standard directional resize cursor, and the user can drag and drop to change the size.