end
  if State.cursor1.pos == nil then
    State.cursor1.pos = 1
  end
  -- hack: insert a text line at bottom of file if necessary
  if State.cursor1.line > #State.lines then
    assert(State.cursor1.line == #State.lines+1)
    table.insert(State.lines, {mode='text', data=''})
    table.insert(State.line_cache, {})
  end
--?   print(y, App.screen.height, App.screen.height-State.line_height)
  if y > App.screen.height - State.line_height then
  State.screen_top1 = {line=State.screen_bottom1.line, pos=State.screen_bottom1.pos}
--?   print('setting top to', State.screen_top1.line, State.screen_top1.pos)

  if State.cursor1.pos == nil then
    State.cursor1.pos = 1
  end

  -- If a line/paragraph gets to a page boundary, I often want to scroll
  -- before I get to the bottom.
  -- However, only do this if it makes forward progress.
  local bot2 = Text.to2(State, State.screen_bottom1)
  if bot2.screen_line > 1 then
    bot2.screen_line = math.max(bot2.screen_line-10, 1)
  end
  local new_top1 = Text.to1(State, bot2)
  if Text.lt1(State.screen_top1, new_top1) then
    State.screen_top1 = new_top1
  else
    State.screen_top1 = {line=State.screen_bottom1.line, pos=State.screen_bottom1.pos}
  end

  State.screen_top1 = {line=State.screen_bottom1.line, pos=State.screen_bottom1.pos}

  end
  if State.cursor1.pos == nil then
    State.cursor1.pos = 1