Eclipse's emacs mode is nothing like Emacs. For example, it binds undo to F9, leaving C-/ (the emacs binding for undo) as "comment this line". WTF. Of course, once you fix the bindings, Eclipse's undo doesn't work anything like Emacs' undo. It's not Emacs, it's Eclipse with C-a (but not M-n) and C-e.