The desktop peek function that temporarily previews the desktop is a new useful feature in Windows 7. Simply move your mouse over to the end of the taskbar, and you will get to see a quick view of what’s on your desktop. When you move it away, all previously faded away open windows reappears right away.
But that feature is disabled in Windows 8 by default. Though you are still able to use the feature with the new keyboard combination, Win+, (comma), you don’t get the same peaking feature when you move the cursor over to that area.
How can I re-enable it? Easy peasy.
Go to Taskbar Properties window by right-clicking Taskbar and choosing Properties, check the option “Use Peek to preview the desktop…” under Taskbar tab, and click OK to save the change.