Created attachment 71795 [details]
a document to edit in the steps to reproduce - it contains a simple conditional format in cell A1

Problem description: when changing existing conditional formatting it is not possible to undo changes as they are not captured by the undo list, so cannot be undone.

Steps to reproduce:
1. open the attached document (or create a simple document with a conditional format, save, close and reopen to clear the undo list)
2A. change the conditional format in cell A1 to be active when the cell value is 2 using: Format -> Conditional formatting -> Condition
3. close the dialogue(s)

Steps to reproduce:
1. open the attached document (or create a simple document with a conditional format, save, close and reopen to clear the undo list)
2B. change the conditional format in cell A1 to be active when the cell value is 2 using: Format -> Conditional formatting -> Manage, and then selecting 'Edit...'
3. close the dialogue(s)

Current behavior: the undo button is deactivated as the change is not captured by the undo list, so it cannot be undone

Expected behavior: the undo button should allow this change to be undone      
Operating System: Windows XP
Version: 4.0.0.0.beta1