plotscript, main, begin
  variable(bar, background)
  background := create rect(320, 200, 1)
  set rect trans(background, trans:fuzzy)
  set rect border(background, border:none)
  bar := create rect(40, 200, 4)
  set rect border(bar, border:none)
  while (true) do (
    # Flip visibility of background every tick
    set slice visible(background, get slice visible(background) ^^ true)

    # Bounce bar betwen left and right end of the screen
    if (not(slice is moving(bar))) then (
      if (slice x(bar) == 0) then (
        move slice by(bar, 320 -- 40, 0, 60)
      ) else (
        move slice by(bar, -320 + 40, 0, 60)
      )
    )

    wait
  )
end