Two documents in one window in LO writer. How?

Some years ago, I saw a strange function in Open Office. I’m not even sure whether I understood it right. Two documents lying on each other with a kind of a „window“ in the upper one, so you could see both the document you were taking notes of and the document you were editing. Did I guess that right? Does there exist such a function? If so, does Libre Office Writer have this?

Thank you.
P.S. Sorry if I understood a completely different function all wrong.

What is your operating system and LibreOffice version?

Tiling does not exists in LibreOffice. But you can probably use tiling on operating system.

Thanks for your answer!
I have Windows 7 Home Premium and Libre Office 4.2. How can I do tiling through the OS?

http://www.howtogeek.com/howto/11073/stupid-geek-tricks-tile-or-cascade-multiple-windows-in-windows-7/

http://www.guidingtech.com/15713/tile-windows-vertically-windows-pc/

Thanks a lot!