So I've got this graphics tablet. A Genius WP-8060U. I got it at an electronics clearinghouse for I think $30 a number of years ago, which because I was using Linux at the time, the purchase was a bit of a gamble. I found the Wizardpen project online and signed up as a tester, so I was able to get it working most of the time. That project died, and support for those drivers was picked up at some point by the Digimend project.
This is a short how-to for restricting a drawing tablet (also known as a graphics tablet) to a single screen. When you have 2, 3, or 4 (or more) monitors, input devices might not work exactly how you want them to because of the difference between desktop size and monitor size (when using big desktop or xinerama. As an example, I have 2x22" monitors, each capable of displaying 1680x1050. My desktop size is therefore 3360x1080, and that is what my tablet maps to.