Try this next time you are working through a problem or developing a new design in Omnigraffle. Each time you add another major component or your mind flips around and you start another approach, just duplicate the canvas you are on and keep going. This will save all the various versions of your thinking with out interrupting the zen like trance you took 3 hours getting into.
Then when you have to stop to go to a meeting you can review your thinking and get right back to where you were.
p.s. i went cold turkey off Viso a couple months ago and i have never looked back!