Rolled up my sleeves and did my first actual norns scripting. 
After a misstep or two I noticed encoders 2 and 3 don’t actually do anything, so I used them as proof of concept scrubbers. By default they scrub tracks 1 and 2. Hold alt to scrub 3 and 4.
I won’t do a pull request or fork just yet, as I want to keep tinkering, and do the scrubbing on the arc as planned.
For those that want it the code change is simple;
function enc(n, d)
if n == 1 then
params:delta(track .. "volume", d)
end
-- begin experimental quad scrubbing enhancement
if n == 2 then
if alt then
scrub(3, d)
else
scrub(1, d)
end
end
if n == 3 then
if alt then
scrub(4, d)
else
scrub(2, d)
end
end
-- end experimental quad scrubbing enhancement
last_enc = n
time_last_enc = util.time()
end
There may be unexpected consequences, but seems ok so far.