No revert or cancel edit in iCal

I have always thought it strange that I couldn't revert changes to an event or cancel an edit in iCal. Now that I have set up iCal with *Exchange 2007*, this has become a critical issue for me. I applaud the addition of this enterprise feature. However when I open an exchange-sourced event I cannot cancel or revert any changes to that event. It's very easy to accidentally key in a change. I tried reverting the change and canceling the edit every way that I knew how. Nothing worked. The critical piece is that when I exit the event I get prompted for 2 undesirable options:

#1 return to edit the event
#2 send update to all meeting attendees

Where is the cancel option?

Please help, thanks.
- Andres