Doing undo and redo while editing nested itemize tags can corrupt nested itemize tags.

The follow is one sequence that leads to corruption:
1) Create two nested itemize tags
2) Enter "a" as the item for the first itemize and "b" as the item of the second level itemize. At this point the itemize looks like

* a
  o b

3) Move the cursor after the character "a" and press Backspace twice to delete the character and the item, to get

  o b

4) press Undo 6 times until everything is gone
5) press Redo 6 times to get back to the state of step 3
6) Press Undo 2 times

At this point the items look like

* aa
  o b

where the character "a" is repeated.

Further undoing and redoing leads to "Error: Exception, future corrupted" being thrown.