This karabiner.json contains two profiles, the default is derived from
SpaceFN and the Caps lock cursor profile is new.
The starting point for this profile is SpaceFN. The idea is that tapping the space bar allows it to work normally, as space. Holding down the space bar (like a modifier key, similar to Shift and Ctrl) allows it to act as a modifier key.
Mucho kudos to Ergoemacs mode who provides something similar, but the settings are more refined to avoid false triggers.
With the standard settings, typing space followed by a letter very quickly could falsely trigger the SpaceFN binding for that letter.
False triggers are avoided by requiring the space bar to be held down for at least 100ms before it starts to act as a modifier.
Also, this profile modifies CapsLock to act as Ctrl when held down and to act as Escape when typed alone. (I don't need CapsLock itself.)
Keybindings (all with space held down):
s- space. This allows keyboard repeat.g- escape.a- cmd-left (beginning of line)e- cmd-right (end of line)h- left (from vi)j- down (from vi)k- up (from vi)l- right (from vi)b- left (from emacs)f- right (from emacs)w- option-right (go word right, from vi)q- option-left (go word left) b from vi is already taken, and q is left of wx- delete forward (delete character, from vi)d- option-delete forward (delete word)m- return (from ctrl-m)p- page upn- page downu- homeo- end1through0- f1 through f10-- f11 (right of 0)=- f12 (right of minus)