I test that code :
function TIC() if btn(0) then sfx(0,34,2,5) elseif btn(1) then sfx(0,34,2,15) else sfx(-1,0,0) end end
But the sound don't stop and there aren't difference with volume parameter.
Why ? (I use 0.15.0 dev version/same problem on 0.16.0)
Others problems detect on 0.16.0:
shortcuts Alt+1..5 don't work (but F1...5 work fine ;) )