elseif lines.current.pending.mode == 'polygon' then
        local mx,my = coord(x-16), coord(y-lines.current.y)
        if mx >= 0 and mx < 256 and my >= 0 and my < lines.current.h then
          local j = insert_point(lines.current.points, mx,my)
          table.insert(lines.current.shapes, lines.current.pending)
        end
        table.insert(lines.current.shapes, lines.current.pending)

        elseif current_mode == 'polygon' then
          local j = insert_point(drawing.points, coord(x-16), coord(y-drawing.y))
          drawing.pending = {mode=current_mode, vertices={j}}

  elseif shape.mode == 'polygon' then
    local prev = nil
    for _,point in ipairs(shape.vertices) do
      local curr = drawing.points[point]
      if prev then
        love.graphics.line(pixels(prev.x)+left,pixels(prev.y)+top, pixels(curr.x)+left,pixels(curr.y)+top)
      end
      prev = curr
    end
    -- close the loop
    local curr = drawing.points[shape.vertices[1]]
    love.graphics.line(pixels(prev.x)+left,pixels(prev.y)+top, pixels(curr.x)+left,pixels(curr.y)+top)

  elseif shape.mode == 'polygon' then
    -- don't close the loop on a pending polygon
    local prev = nil
    for _,point in ipairs(shape.vertices) do
      local curr = drawing.points[point]
      if prev then
        love.graphics.line(pixels(prev.x)+left,pixels(prev.y)+top, pixels(curr.x)+left,pixels(curr.y)+top)
      end
      prev = curr
    end
    love.graphics.line(pixels(prev.x)+left,pixels(prev.y)+top, love.mouse.getX(),love.mouse.getY())

  elseif shape.mode == 'polygon' then
    return on_polygon(x,y, drawing, shape)

function on_polygon(x,y, drawing, shape)
  local prev
  for _,p in ipairs(shape.vertices) do
    if prev then
      if on_line(x,y, drawing, {p1=prev, p2=p}) then
        return true
      end
    end
    prev = p
  end
  return on_line(x,y, drawing, {p1=shape.vertices[1], p2=shape.vertices[#shape.vertices]})
end

  elseif chord == 'C-g' then
    current_mode = 'polygon'
  elseif love.mouse.isDown('1') and chord == 'p' and current_mode == 'polygon' then
    local drawing = current_drawing()
    local mx,my = coord(love.mouse.getX()-16), coord(love.mouse.getY()-drawing.y)
    local j = insert_point(drawing.points, mx,my)
    table.insert(drawing.pending.vertices, j)