At work I recently came across a trackball. It was about to be thrown away and since I’d never really used one I decided to take it home and try it out. It’s a Logitech Trackman Marble, still for sale on Logitech’s website.
The trackball features four buttons: two large ones for left and right-clicking and to smaller ones that work as back and forward buttons in Firefox, for example.
After plugging it into my PC it was instantly recognised by X (I’m using Ubuntu 10.04). There’s no middle mouse button, but that can be emulated by clicking the left and right mouse buttons at the same time (something I’ve been use to on older laptops, and, well, even from the time that some of the mouses I owned only had two buttons). However, I did miss my scroll wheel. A quick search on the Internet brought me to Rob Meerman’s website where he explains a lot about the Trackman and how it works in X. He even has a special section on Ubuntu 10.04. In short it comes down to these commands:
xinput set-int-prop "Logitech USB Trackball" "Evdev Wheel Emulation Button" 8 8 xinput set-int-prop "Logitech USB Trackball" "Evdev Wheel Emulation" 8 1
Unfortunately the changes made by these commands are not persistent across reboots. I’ll try to fix that later.
EDIT: To add middle mouse button emulation and horizontal scrolling (thanks to rejistania below) run:
xinput set-int-prop "Logitech USB Trackball" "Evdev Middle Button Emulation" 8 1 xinput set-prop "Logitech USB Trackball" "Evdev Wheel Emulation Axes" 6 7 4 5
Regarding the use of a trackball compared to an ordinary mouse my experiences so far have been very positive. It didn’t take me a lot of time to get used to it. Also precision placement of the pointer doesn’t seem to be more difficult that with a regular mouse. So for now my wireless Logitech mouse can take a holiday :-). The nicest think about the trackball is the fact that you don’t have to move the whole device. So it’s less ‘weight lifting’. Also, the fact that the ball (in combination with the small button) is the scroll wheel, makes for a relatively heavy wheel without much friction, so scrolling large distances can simply be done by giving the ball a good spin. Nice!