function edit.check_locs(State)
  -- if State is inconsistent (i.e. file changed by some other program),
  --   throw away all cursor state entirely
  if edit.invalid1(State, State.screen_top1)
      or edit.invalid1(State, State.cursor1)
      or not Text.le1(State.screen_top1, State.cursor1) then
    State.screen_top1 = {line=1, pos=1}
  end
end
function edit.invalid1(State, loc1)
  return loc1.line > #State.lines
      or loc1.pos > #State.lines[loc1.line].data
end
    State.cursor1 = {line=1, pos=1}

  edit.check_locs(Editor_state)
  -- We currently start out with side B collapsed.
  -- Other options:
  --  * save all expanded state by line
  --  * expand all if any location is in side B
  if Editor_state.cursor1.line > #Editor_state.lines then
    Editor_state.cursor1 = {line=1, pos=1}
  end
  if Editor_state.screen_top1.line > #Editor_state.lines then
    Editor_state.screen_top1 = {line=1, pos=1}
  end
  edit.eradicate_locations_after_the_fold(Editor_state)
  if rawget(_G, 'jit') then
    jit.off()
    jit.flush()
  end
end
function source.load_settings()
  local settings = Settings.source
  love.graphics.setFont(love.graphics.newFont(settings.font_height))
  -- maximize window to determine maximum allowable dimensions

  edit.check_locs(Editor_state)
  love.window.setTitle('text.love - '..Editor_state.filename)
end
function run.draw()
  edit.draw(Editor_state)
end
function run.update(dt)
  Cursor_time = Cursor_time + dt
  edit.update(Editor_state, dt)
end
function run.quit()
  edit.quit(Editor_state)
end
function run.settings()
  edit.check_locs(Editor_state)
  love.window.setTitle('text.love - '..Editor_state.filename)
  if #arg > 1 then
    print('ignoring commandline args after '..arg[1])
  end
  if rawget(_G, 'jit') then
    jit.off()
    jit.flush()
  end
end
function run.load_settings()
  love.graphics.setFont(love.graphics.newFont(Settings.font_height))

    next_save = nil,
    -- undo
    history = {},
    next_history = 1,
    -- search
    search_term = nil,
    search_text = nil,
    search_backup = nil,  -- stuff to restore when cancelling search
  }
  return result
end  -- App.initialize_state

function edit.fixup_cursor(State)

function edit.check_locs(State)
  -- if State is inconsistent (i.e. file changed by some other program),
  --   throw away all cursor state entirely
  if edit.invalid1(State, State.screen_top1)
      or edit.invalid1(State, State.cursor1)
      or not edit.cursor_on_text(State)
      or not Text.le1(State.screen_top1, State.cursor1) then
    State.screen_top1 = {line=1, pos=1}
    edit.put_cursor_on_first_text_line(State)
  end
end
function edit.invalid1(State, loc1)
  return loc1.line > #State.lines
      or loc1.pos > #State.lines[loc1.line].data
end
function edit.cursor_on_text(State)
  return State.cursor1.line <= #State.lines
      and State.lines[State.cursor1.line].mode == 'text'
end
function edit.put_cursor_on_first_text_line(State)

  for i,line in ipairs(State.lines) do
    if line.mode == 'text' then

      State.cursor1.line = i

      break
    end
  end
end

  edit.check_locs(Editor_state)