Control-Z editing HTML erases all changes since last save

[lmarks]

I was directly editing the one line of the HTML in an HTML block and realized I had deleted a few more characters than intended. I hit Ctrl-Z to restore the last change.

TWO undesirable things happened.
1) When the page refreshed, it was positioned at the top of the page, not where I had been working. (This has been reported before, but has never been fixed.)
2) When I scrolled down to the point where I had been working, all the lines I had entered since the last save (about 10 minutes work) was gone, not just the last change I made. Surely this is not the expected behavior!

I would be happy to help the responder reproduce this problem.