macrakis@UUNET.UU.NET (Stavros Macrakis) (12/28/88)
GNU Emacs 18.50.3 of Wed Aug 17 1988 on rigel (usg-unix-v) It might be nice if outline show/hide actions were undoable. Obviously, no information is lost by these actions, so undo is not needed to save the user from errors, however undo has another useful property: it reassures users. Especially for novices, knowing that any action can be undone encourages experimentation. (Of course, there's always show-all in the outline case...) In looking at the code, I noticed that undo records are always in the form of characters saved. If this is not considered efficient enough, it might be useful to have the equivalent of unwind-protect, that is, to allow an action to specify its own undo action. Such a mechanism could be useful in other cases where little information is lost but many characters in the buffer are changed. Note also that undoability and bf_modified should probably be decoupled.