Design table exiting without saving problem

I have run into this more than once and wonder if there is a simple
solution.

Open a design table in a new window to make changes. Have everthing
done, great - looks good, exit to update SW, and have SW tell you that
something is not valid, therefore we are dumping ALL your changes.
Tough luck Charlie. Open it back up to fix the error, and sure enough,
everything you had just done is gone. Am I missing the obvious other
than manually saving a backup copy each time?

WT