-- keyboard update
		local key_up = opt.vertical and 'up' or 'right'
		local key_down = opt.vertical and 'down' or 'left'
		if core:getPressedKey() == key_up then
			info.value = math.min(info.max, info.value + info.step)
			value_changed = true
		elseif core:getPressedKey() == key_down then
			info.value = math.max(info.min, info.value - info.step)
			value_changed = true
		end

It seems can't use mouse with step variable. And it also not work with keyboard beacuse there is no way to active slider when you want to use keyboard.