The famous Logitech Trackman MarbleFX trackball has four buttons, of which the 4th (red) button was used to emulate a scroll wheel. To enable this, the trackball needs to be switched into a special ...

The Program button remains the unconditional fallback for an image that will not run at all. Note the two USB paths need different groups, and the login is stale, so both need a wrapper: sg dialout -c ...