exiting from gnome

[Greg Troxel]

  This is probably slightly easier than reading log files, and will
  handle data _other_ that just transactional changes....  However
  we would need to be careful about this -- it should only happen for
  _some_ backends (i.e. only the File Backend).  Perhaps that means
  we need an extension to the Backend API to add an 'autosave()' api?

Speaking without enough clue as to the Backend API - feel free to
flame me....

Well, it should happen for any backends which are capable of
supporting autosave and for which autosave is meaningful.  That may
well be only File right now, but any backend that has the concept of
'save' should have the concept of 'autosave'.  For a DB backend, the
whole notion of 'save' is perhaps missing, and perhaps an API
predicate is needed to guide UI choices about save/modified-status
etc. kinds of behavior.  The persistence-at-all-times model is
different than the modified/save model, and the UI has to reflect
these in a way that makes sense.  E.g., perhaps the save button should
always be greyed out when using persistence-at-all-times backends.

Adding autosave to the Backend API makes a lot of sense.  Once also
has to add a way to check for autosave files on startup, and some way
to get status about them and then read them.  IMHO this should be
similar to the emacs behavior, with options to delete the autosave
data or read it in.