It would sure be nice if you could double click an event in the history list to get back to that point instead of selecting the event and then clicking ok. I find myself after all these years still double clicking the events and expecting the history to go to that point in the project...
 
Well, I guess as long as the history list is built correctly.

That's a good idea!  I would also like it if Sonar would recognized a previously saved version of a song and not prompt to be saved.  IOW, after doing several edits, I sometimes undo them back to the state that was previously saved, and Sonar puts the asterisk next to the song title, prompting a save.  My Sony software recognizes when you've returned to a saved state and removes the asterisk from the song title.  Just a small quibble.

I can't see how this could be implemented as any previous action could and often does impact on subsequent events.
 
Does that make sense? I think my head is still full of Bacardi this morning. 
 
Let's say you insert a track, record some audio and then apply a volume envelope.
What would happen if you simply undid the recording?

It might roll back the Bacardi too?