Dragging desktop - how should it work?

There's one feature I really don't understand in Windows 8. I move mouse to the top of the screen, and now I can drag desktop and push it to right/left side of my display. The rest of the screen is empty, there are no even metro apps (I expected it because it would at least make more sense than blank space). Can anybody figure out what this feature is for?

I am sure someone can enlighten you, but it may have something to do with dual monitors. I don't have one, so cant test it. last guess is it is somewhat a bug? It could be associated with the metro drag feature and maybe modified with future updates.

It's something you can do with any Metro app, or the desktop (which is treated like a Metro app). Drag to the bottom of the screen, and the app (or the desktop in this case) closes. Drag to the left or the right, and the app (or desktop) gets docked to the side of the screen, allowing you to open another app in the main part of the screen.