The taskbar’s main duty is to play host to a set of buttons that represent the open windows on the desktop. You can switch to any window by clicking its taskbar button. In theory, it should be straightforward to choose the taskbar button for the window you want to activate because each button shows the window title and the icon associated with the program. In practice, however, picking out the correct taskbar button is often problematic because many window titles don’t fit entirely inside the button. This is particularly true of documents, which tend to have longish names. The situation worsens as you open more windows because the more buttons there are on the taskbar, the smaller each button becomes.
The "solution" to this dilemma has long been the pop-up banners that appear when you hover the mouse pointer over a taskbar button. These banners show you the full title of the window. The pop-ups help, but you can still have problems figuring out the correct button if you have opened several documents that use similar names.
What you really need to know in these cases is what’s inside each window, and Vista has just the thing: taskbar preview windows. When you hover your mouse pointer over a taskbar button in Vista, the WPF displays not only the window title, but also a thumbnail image of the window. As you’ve probably guessed by now, these thumbnails are live, so they show real-time changes to the window state, such as a running video. Figure 3.15 shows an example of a taskbar preview window.
Figure 3.15 When you hover the mouse pointer over a taskbar button in Windows Vista, a live thumbnail of the window appears.
One of Windows XP’s solutions to taskbar clutter was to group similar taskbar buttons together. For example, if you had several Internet Explorer windows open, XP would show just a single Internet Explorer taskbar button with an arrow. Clicking the arrow displayed a list of the open Internet Explorer windows, and you could then click the window you wanted to activate.
Windows Vista keeps this feature, but with a slight twist. When you hover your mouse pointer over a button representing a group of windows, a stacked thumbnail appears, as shown in Figure 3.16. The thumbnail that appears at the front of the stack is the window that you opened first. Note, however, that you cannot navigate the stack, so this version of the taskbar thumbnails is not all that useful.
Figure 3.16 When you hover the mouse pointer over a grouped taskbar button, a stacked thumbnail appears.