The first laptop I used regularly was a GRiD, not surprising since I was working there. I don’t recall the exact model, but I remember I loved its pointing device which was an Isobar. I haven’t seen one since and I have difficulty describing it to people. A web search revealed that the Outbound Notebook, a Macintosh portable “clone” (they could not legally sell the Mac ROMS so they were somewhat doomed), also featured this device. You can see the Isobar in the photos and there’s a description: “a metal tube located just below the keyboard. It can roll forwards and back, or slide left and right.” Because of the length of the tube, you could use either (or both) thumbs to control the movement, and you could press down for a mouse click. I became very accustomed to it and struggled with all subsequent portable pointing devices with the exception of IBM’s Trackpoint.