if State.cursor1.pos then
    Text.upA(State)
  else
    Text.upB(State)
  end
end
function Text.upA(State)

function Text.upB(State)
  local line_cache = State.line_cache[State.cursor1.line]
  local screen_line_starting_posB, screen_line_indexB = Text.pos_at_start_of_screen_lineB(State, State.cursor1)
  assert(screen_line_indexB >= 1)
  if screen_line_indexB == 1 then
    -- move to A side of previous line
    if State.cursor1.line > 1 then
      State.cursor1.line = State.cursor1.line-1
      State.cursor1.posB = nil
      local prev_line_cache = State.line_cache[State.cursor1.line]
      local prev_screen_line_starting_pos = prev_line_cache.screen_line_starting_pos[#prev_line_cache.screen_line_starting_pos]
      local prev_screen_line_starting_byte_offset = Text.offset(State.lines[State.cursor1.line].data, prev_screen_line_starting_pos)
      local s = string.sub(State.lines[State.cursor1.line].data, prev_screen_line_starting_byte_offset)
      State.cursor1.pos = prev_screen_line_starting_pos + Text.nearest_cursor_pos(s, State.cursor_x, State.left) - 1
    end
  elseif screen_line_indexB == 2 then
    -- all-B screen-line to potentially A+B screen-line
    local xA = Margin_left + Text.screen_line_width(State, State.cursor1.line, #line_cache.screen_line_starting_pos) + AB_padding
    if State.cursor_x < xA then
      State.cursor1.posB = nil
      local new_screen_line_starting_pos = line_cache.screen_line_starting_pos[#line_cache.screen_line_starting_pos]
      local new_screen_line_starting_byte_offset = Text.offset(State.lines[State.cursor1.line].data, new_screen_line_starting_pos)
      local s = string.sub(State.lines[State.cursor1.line].data, new_screen_line_starting_byte_offset)
      State.cursor1.pos = new_screen_line_starting_pos + Text.nearest_cursor_pos(s, State.cursor_x, State.left) - 1
    else
      local new_screen_line_starting_posB = line_cache.screen_line_starting_posB[screen_line_indexB-1]
      local new_screen_line_starting_byte_offsetB = Text.offset(State.lines[State.cursor1.line].dataB, new_screen_line_starting_posB)
      local s = string.sub(State.lines[State.cursor1.line].dataB, new_screen_line_starting_byte_offsetB)
      State.cursor1.posB = new_screen_line_starting_posB + Text.nearest_cursor_pos(s, State.cursor_x-xA, State.left) - 1
    end
  else
    assert(screen_line_indexB > 2)
    -- all-B screen-line to all-B screen-line
    local new_screen_line_starting_posB = line_cache.screen_line_starting_posB[screen_line_indexB-1]
    local new_screen_line_starting_byte_offsetB = Text.offset(State.lines[State.cursor1.line].dataB, new_screen_line_starting_posB)
    local s = string.sub(State.lines[State.cursor1.line].dataB, new_screen_line_starting_byte_offsetB)
    State.cursor1.posB = new_screen_line_starting_posB + Text.nearest_cursor_pos(s, State.cursor_x, State.left) - 1
  end
  if Text.lt1(State.cursor1, State.screen_top1) then
    local top2 = Text.to2(State, State.screen_top1)
    top2 = Text.previous_screen_line(State, top2)
    State.screen_top1 = Text.to1(State, top2)
  end
end