[ubuntu] Need multiple documents on one screen

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http://ubuntuforums.org – I've just recently upgraded to Ubuntu 12 and find I suddenly lost the ability to have several documents on the screen at once. At first there was no problem, but then something happened and now each document takes up the whole screen. So I have been converting them over to Word and using Microsoft XP which does a good job. But I would rather use Ubuntu. How do I have the program give me several documents at once that are easy to switch between like they are in XP? (Hardware)