Undo...

  Choose Undo...  to cancel a number of edits.  A dialog box
  appears.

  Click on the Undo button to cancel one edit at a time.  Click
  on the Redo button to reinstate one edit at a time, beginning
  with the most recently undone edit.  Click on the Cancel
  button to remove the dialog box from the screen.

  Additional topics:

  *   Undo

  *   Redo

  *   Cut

  *   Copy

  *   Paste

  *   Clear

  *   Select All