I did a boolean operation with keep part turned off, then did a BUNCH of work, and decided I should have kept part. I used undo about 120 steps, saved the parts as a temp file and was horrified to find I'd lost all my redo steps, so could not get back to where I was.
Save_package should not destroy all redo steps
Check part properties without changing any properties should not destroy all redo steps
Please add to the list of things that should not destroy all redo steps, but currently do.