New version after 9 days

The good news is the last version lasted 9 days. The bad news is carousel-az-safe.love  was catastrophically broken for all 9 of those days. So much for "safe" :( I'm going to try harder to use both versions that I put out.

Other updates in this version:

• We do a little better about saving settings across restart. Saving settings is still unreliable on mobile platforms. In particular, Carousel will unfortunately forget your list of open screens every time you update to a new version. Please report if it forgets your open screens any other time. The _contents_ of screens that have been saved to file should never, ever be lost.
• Bug: scripts changing the font would mess up the UI. Carousel should now isolate font changes in your scripts from its UI.
• Bug: Errors were being prepended to the output buffer. Now they're appended.
• 2 new abbreviations in the abbreviation screen for math.floor and math.ceil.

As recompense for this issue, a humble program for your consideration, where populations of cell duke it out in an epic battle on the infinite (toroidal) surface of the Game of Life:

math.randomseed(os.time())
N = 6
W, H = ceil(Safe_width/N), ceil(Safe_height/N)
running = false
curr_color = {rand(), rand(), rand()}
curr, new = {}, {}
for x=1,W do
  table.insert(curr, {})
  table.insert(new, {})
  for y=1,H do
    table.insert(curr[x], {v=0, c={0,0,0}})
    table.insert(new[x], {v=0, c={0,0,0}})
  end end
function car.draw()
  for x=1,W do
    for y=1,H do
      if curr[x][y].v > 0 then
        color(unpack(curr[x][y].c))
        rect('fill', x*N, y*N, N-1,N-1)
      end end end
  if not running then
    local w = App.width('run')
    color(0,0,1,0.4)
    rect('fill', 60, 35, w+10,Line_height+10)
    color(0,0,0)
    rect('line', 60, 35, w+10,Line_height+10)
    g.print('run', 65, 40)
    color(unpack(curr_color))
    rect('fill', Safe_width-100, 35, 60,Line_height+10)
    color(0,0,0)
    rect('line', Safe_width-100, 35, 60, Line_height+10)
  end
end
function car.mousepressed(x,y)
  if running then return end
  if y > 30 and y < 35+Line_height+10 then
    if x < 200 then
      running = true
    elseif x > Safe_width-100 then
      curr_color = {rand(), rand(), rand()}
    end
  end
end
function car.update(dt)
  if running then
    step()
  elseif not Show_code and App.mouse_down(1) then
    local x,y = love.mouse.getPosition()
    set(floor((x-1)/N)%W+1, floor((y-1)/N)%H+1)
  end
end
function set(x,y)
  curr[x][y].v = 1
  local s, d = curr_color, curr[x][y].c
  d[1], d[2], d[3] = s[1], s[2], s[3]
end
function step()
  for x=1,W do
    for y=1,H do
      local n = nghs(x,y)
      if n < 2 or n > 3 then
        new[x][y].v = 0
      elseif n == 2 or n == 3 and curr[x][y].v > 0 then
        cpy(x,y)
      else
        -- n=3, birth
        new[x][y].v = 1
        -- copy some random live neighbor's color over
        local oldc = random_color(x,y)
        local c = new[x][y].c
        c[1], c[2], c[3] = oldc[1], oldc[2], oldc[3]
      end end end
  curr, new = new, curr
end
function nghs(x,y)
  return v(x-1,y-1) + v(x,y-1) + v(x+1,y-1)
    + v(x-1,y)          + v(x+1,y)
    + v(x-1,y+1) + v(x,y+1) + v(x+1,y+1)
end
function v(x,y)
  return curr[(x-1)%W+1][(y-1)%H+1].v
end
function cpy(x,y)
  new[x][y].v = curr[x][y].v
  local c, oldc = new[x][y].c, curr[x][y].c
  c[1], c[2], c[3] = oldc[1], oldc[2], oldc[3]
end
function random_color(x,y)
  local rgbs = {}
  maybe_append_color(x-1, y-1, rgbs)
  maybe_append_color(x-1, y, rgbs)
  maybe_append_color(x-1, y+1, rgbs)
  maybe_append_color(x, y-1, rgbs)
  maybe_append_color(x, y+1, rgbs)
  maybe_append_color(x+1, y-1, rgbs)
  maybe_append_color(x+1, y, rgbs)
  maybe_append_color(x+1, y+1, rgbs)
  return rgbs[rand(#rgbs)]
end
function maybe_append_color(x,y, out)
  x,y = (x-1)%W+1, (y-1)%H+1
  if curr[x][y].v > 0 then table.insert(out, curr[x][y].c) end
end

If you try pasting this program into Lua Carousel, remember to first run the abbreviations on one of the example screens. Or if you've deleted that screen, here are the abbreviations this program uses:

g = love.graphics
rect = g.rectangle
color = g.setColor
rand = math.random
floor, ceil = math.floor, math.ceil