How to Turn Open Window Thumbnail Previews On or Off for the Taskbar in Vista
This shows a thumbnail view of currently open windows on the taskbar when you move your mouse pointer over the tab of a open window on the taskbar. This will show you how to turn the Taskbar open window thumbnail previews on or off in Vista.
This is not available in the Vista Home Basic version even though the option is there to select.This can be helpful for a quick view of the current open windows without actually having to go to a window.You must have the Windows Aero color scheme turned on for the Glass Transparency, Taskbar Thumbnail Previews, and Flip 3D features.
HARDWARE REQUIREMENTS FOR: WINDOWS AERO
For more on this, see: Windows Help and Support...