What command does Alt-Backspace do? It seems to undo largish swaths of things, but interferes with the real undo, leaving it's handiwork un-undoable. Actually, it's not obvious what it's exactly doing. I hit Alt-Backspace occasionally by accident because it's the Emacs and Bash shell command for "backspace over previous word".
It would be nice if it did nothing when I accidentally hit it (like how Alt-Delete does nothing).
---John