Dual monitors in Xubuntu precise

[Kevin O'Gorman]

I have a laptop with HDMI output for a second monitor.  It dual boots
Win 7 and Precise.

I attached a second monitor, and Windows could make it mirror the main
display or (my preference) extend the desktop.

Under Xubuntu, it mirrors the main display, and I cannot see anything
to change that to extend the display.  Probably I need to install
something, but I don't know what.

My desktop is similar, but it's got an Nvidia controller, so I can't
use it as a model.

The laptop is a recent Gateway.  I don't know the video hardware or
how to find out what it is, but I don't think it's NVidia.

I could use some help, obviously.

--
Kevin O'Gorman

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