This option will Undo the last major delete operation.
This options undoes the last deletion for points, strings, text and viewports.
This menu option can also be invoked by the keyboard sequence Ctrl/Z.
If no items have been deleted, this option will be greyed out to indicate that it
cannot be used. When one or more items are deleted, say points,
the menu items will prompt with ‘Undo 5 Deleted Points’ to indicate what the Undo action will do.