Ronning out of Undo

[SMcNeill]

What I meant was, If I change my Undo size to zero, then IMMEDIATELY, reset it to say 1000, is this like flushing the Undo?
(and if so, could this maybe be built into an optional command?) 
If I'm happy with the prog to that point, would this be a reasonable option?

I had to test this just to be certain, but it does indeed work like that. (Though 10 is the minimal size.)

Change size to 10, save it... The old undo file gets erased and blanked.
Change it back to 1000, it's still a zero byte file.

I don't really see the point in flushing the undo file though. I've never really noticed where it's affected performance one way or another, regardless of size.