Sure, but i think the innovation was the dedicated leap keys. You hold the key, type to incrementally search, and let go to leap. One key for forward and one for back.
Also, leaping was through eveything in the whole os, not just the application.
Since almost everyone uses USB keyboards, I am surprised that a small addon board with just 2 keycaps that can be placed near the spacebar, hasn't already been made. Could do it with a Teensy or anything else that exposes HID, I think.
It actually works really well; it uses the left and right alt keys as the open and solid Apple keys, which the SwyftCard uses as forward and backward leaping. It's quite easy and comfortable to use!
> Since almost everyone uses USB keyboards, I am surprised that a small addon board with just 2 keycaps that can be placed near the spacebar, hasn't already been made. Could do it with a Teensy or anything else that exposes HID, I think.
I've seen something (on HN in the past, maybe?) similar - someone developed pedals (maybe for Vim?)
The interface should not be too hard to reimplement as an emacs mode.
One more project on the "someday" list...