[Archive] Use button4 & cursor to scroll (for my Logitech Trackman Marble)

HammerspoonTrackball.lua

-- HANDLE SCROLLING
local oldmousepos = {}
-- positive multiplier (== natural scrolling) makes mouse work like traditional scrollwheel
local scrollmult = 4 

-- The were all events logged, when using `{"all"}`
mousetap = hs.eventtap.new({0,3,5,14,25,26,27}, function(e)
  oldmousepos = hs.mouse.getAbsolutePosition()
	local mods = hs.eventtap.checkKeyboardModifiers()
    local pressedMouseButton = e:getProperty(hs.eventtap.event.properties['mouseEventButtonNumber'])

    -- If OSX button 4 is pressed, allow scrolling
    local shouldScroll = 3 == pressedMouseButton
    if shouldScroll then
		local dx = e:getProperty(hs.eventtap.event.properties['mouseEventDeltaX'])
		local dy = e:getProperty(hs.eventtap.event.properties['mouseEventDeltaY'])
		local scroll = hs.eventtap.event.newScrollEvent({dx * scrollmult, dy * scrollmult},{},'pixel')
		scroll:post()
		
		-- put the mouse back
		hs.mouse.setAbsolutePosition(oldmousepos)
		
		return true, {scroll}
	else
		return false, {}
	end
	-- print ("Mouse moved!")
	-- print (dx)
	-- print (dy)
end)
mousetap:start()

Original: pqrs-org/Karabiner-archived#814