I have a dual monitor setup, and I am using Ubuntu 12.04 LTS
I have changed the positioning of the monitors several times, and now for some reason some of the windows open up off-screen (outside of both screens), Update Manager, for instance.
How can I position the windows on one of my screens?
You can get the window back on your screen by using
ALT + spacebar
This would show you the maximize/minimize/ ... options. Click maximize and it would occupy your screen.