local byte_offset = Text.offset(p.name, len-1)
        if len == 1 then byte_offset = 0 end
        p.name = string.sub(p.name, 1, byte_offset)
        record_undo_event(State, {before=before, after=snapshot(State, State.lines.current_drawing_index)})

        if len > 0 then
          local byte_offset = Text.offset(p.name, len-1)
          if len == 1 then byte_offset = 0 end
          p.name = string.sub(p.name, 1, byte_offset)
          record_undo_event(State, {before=before, after=snapshot(State, State.lines.current_drawing_index)})
        end

function test_name_point_then_hit_backspace()
  -- create a drawing with a line
  App.screen.init{width=Test_margin_left+256, height=300}  -- drawing coordinates 1:1 with pixels
  Editor_state = edit.initialize_test_state()
  Editor_state.filename = 'foo'
  Editor_state.lines = load_array{'```lines', '```', ''}
  Text.redraw_all(Editor_state)
  Editor_state.current_drawing_mode = 'line'
  edit.draw(Editor_state)
  -- draw a line
  edit.run_after_mouse_press(Editor_state, Editor_state.left+5, Editor_state.top+Drawing_padding_top+6, 1)
  edit.run_after_mouse_release(Editor_state, Editor_state.left+35, Editor_state.top+Drawing_padding_top+36, 1)
  local drawing = Editor_state.lines[1]
  check_eq(#drawing.shapes, 1, 'baseline/#shapes')
  check_eq(#drawing.points, 2, 'baseline/#points')
  check_eq(drawing.shapes[1].mode, 'line', 'baseline/shape:1')
  local p1 = drawing.points[drawing.shapes[1].p1]
  local p2 = drawing.points[drawing.shapes[1].p2]
  check_eq(p1.x, 5, 'baseline/p1:x')
  check_eq(p1.y, 6, 'baseline/p1:y')
  check_eq(p2.x, 35, 'baseline/p2:x')
  check_eq(p2.y, 36, 'baseline/p2:y')
  check_nil(p2.name, 'baseline/p2:name')
  -- enter 'name' mode without moving the mouse
  edit.run_after_keychord(Editor_state, 'C-n')
  check_eq(Editor_state.current_drawing_mode, 'name', 'mode:1')
  -- hit backspace
  edit.run_after_keychord(Editor_state, 'backspace')
  -- no crash
end