The source for a cube timer application.

CubeTimer.lua

--[[
Cube Timer
Version 3.1
]]

local start_keys = {"lctrl", "ralt"}
local start_keys_down = {false, false}
local keys_down = false
local keys_down_last = false

local elapsed = 0
local start_keys_pressed = false
local timing = false
local timer_armed = false

local time_font
local detail_font

function format_time(time)
	local seconds = tostring(math.floor(time % 60))
	local decimal = tostring(time % 60):match("%.%d%d")
	local minutes = tostring(math.floor(time / 60))

	if (decimal) then
		if (decimal:len() < 2) then
			decimal = decimal .. "0"
		end
	else
		decimal = ".00"
	end

	if (seconds:len() < 2) then
		seconds = "0" .. seconds
	end

	if (minutes:len() < 2) then
		minutes = "0" .. minutes
	end

	return minutes .. ":" .. seconds .. decimal
end

function love.load()
	time_font = love.graphics.newFont("pixel_arial.ttf", 72)
	detail_font = love.graphics.newFont("pixel_arial.ttf", 12)
	stop_font = love.graphics.newFont("pixel_arial.ttf", 26)
end

function love.update(delta)
	keys_down_last = keys_down
	keys_down = true

	for index, key in next, start_keys do
		local down = love.keyboard.isDown(key)
		start_keys_down[index] = down

		if (not down) then
			keys_down = false
		end
	end

	if (timing) then
		elapsed = elapsed + delta

		if (keys_down and not keys_down_last) then
			timing = false
		end
	else
		if (keys_down and not keys_down_last) then
			elapsed = 0
			timer_armed = true
		elseif (not keys_down and timer_armed) then
			timer_armed = false
			timing = true
		end
	end
end

function love.draw()
	if (timing) then
		love.graphics.setColor(0, 200, 0)
	else
		love.graphics.setColor(200, 0, 0)
	end

	love.graphics.setFont(time_font)
	love.graphics.print(format_time(elapsed), 8, 8)

	for index, value in next, start_keys_down do
		if (value) then
			love.graphics.setColor(0, 200, 0)
		else
			love.graphics.setColor(200, 0, 0)
		end

		love.graphics.rectangle("fill", 8 + (60 * index) - 60, 90, 50, 30)

		love.graphics.setColor(255, 255, 255)
		love.graphics.setFont(detail_font)
		love.graphics.print(start_keys[index], 20 + (60 * index) - 60, 97)
	end
end

Yay.