You can allow the end user to undo and redo various user actions, including cell
editing, copying, and pasting from the Clipboard, as well as other actions.
With the undo/redo feature, you can add the capability to your application to undo
various actions in the spreadsheet performed by your end user. To do so, you make
use of the UndoAction class and several specific classes that correspond with various
user actions. There is also a manager class that keeps track of the end-user actions
that can be undone and re-done.