hand cursor drags desktop area..what is the use of this ?

I discovered by chance that approaching mouse cursor to the taskbar it turns into a hand that can drag the desktop area. What is the use of this ?
Please find it enclosed an image on which you see what I am talking about.
Thanks

There are several reasons for this. First, the "Desktop" Is an App, so it can be closed, just like any app. You can drag it down from the top of the screen to the bottom.

Second, you can drag the desktop to the sides and do a "Snap" feature to show desktop alongside a metro app.

I´ve dragged to both sides to find that it snaps to nothing. Perhaps I do not know how to use it.

Here's a screen shot of a desktop and Bing App running side by side. Just drag down and toward the left or right side then you'll see a vertical line then snap to the left or to the right.

Or watch this video:
Using the Split Screen for Win 8 Apps - YouTube

I see.
Before I give it a try is it easy to undo ?
Thanks for posting your answer

Nothing to undo. If you want to close the app then move the mouse cursor to the top until you see a hand cursor, keep holding the left mouse button and drag it down to the bottom.

Thank you for replying.

Also, if you want to enlarge an app full screen drag the dividing line with mouse cursor or finger all the way right or left. If you want to enlarge one and shrink the other, drag the dividing line to a certain point. I'm on my phone, but I believe it will show you when to stop.

Hope that helps.