function test_undo_move_point()
  io.write('\ntest_undo_move_point')
  -- create a drawing with a line
  Filename = 'foo'
  App.screen.init{width=Margin_left+300, height=300}
  Lines = load_array{'```lines', '```', ''}
  Line_width = 256  -- drawing coordinates 1:1 with pixels
  Current_drawing_mode = 'line'
  App.draw()
  App.run_after_mouse_press(Margin_left+5, Margin_top+Drawing_padding_top+6, 1)
  App.run_after_mouse_release(Margin_left+35, Margin_top+Drawing_padding_top+36, 1)
  local drawing = Lines[1]
  check_eq(#drawing.shapes, 1, 'F - test_undo_move_point/baseline/#shapes')
  check_eq(#drawing.points, 2, 'F - test_undo_move_point/baseline/#points')
  check_eq(drawing.shapes[1].mode, 'line', 'F - test_undo_move_point/baseline/shape:1')
  local p1 = drawing.points[drawing.shapes[1].p1]
  local p2 = drawing.points[drawing.shapes[1].p2]
  check_eq(p1.x, 5, 'F - test_undo_move_point/baseline/p1:x')
  check_eq(p1.y, 6, 'F - test_undo_move_point/baseline/p1:y')
  check_eq(p2.x, 35, 'F - test_undo_move_point/baseline/p2:x')
  check_eq(p2.y, 36, 'F - test_undo_move_point/baseline/p2:y')
  check_nil(p2.name, 'F - test_undo_move_point/baseline/p2:name')
  -- move p2
  App.run_after_keychord('C-u')
  App.mouse_move(Margin_left+26, Margin_top+Drawing_padding_top+44)
  App.update(0.05)
  local p2 = drawing.points[drawing.shapes[1].p2]
  check_eq(p2.x, 26, 'F - test_undo_move_point/x')
  check_eq(p2.y, 44, 'F - test_undo_move_point/y')
  -- exit 'move' mode
  App.run_after_mouse_click(Margin_left+26, Margin_top+Drawing_padding_top+44, 1)
  check_eq(Next_history, 4, 'F - test_undo_move_point/next_history')
  -- undo
  App.run_after_keychord('C-z')
  App.run_after_keychord('C-z')  -- bug: need to undo twice
  local drawing = Lines[1]
  local p2 = drawing.points[drawing.shapes[1].p2]
  check_eq(Next_history, 2, 'F - test_undo_move_point/next_history')
  check_eq(p2.x, 35, 'F - test_undo_move_point/x')
  check_eq(p2.y, 36, 'F - test_undo_move_point/y')
  -- change is saved
  Lines = load_from_disk(Filename)
  local p2 = Lines[1].points[drawing.shapes[1].p2]
  check_eq(p2.x, 35, 'F - test_undo_move_point/save/x')
  check_eq(p2.y, 36, 'F - test_undo_move_point/save/y')
end

  moving points