Joël> Does a such mode exists, and if not, is it difficult to do ? Emacs widgets (widget.el and related) do this. They are the foundation of the Customize user interface. However, they don't know how to parse a buffer and put r/o properties on it; they insert r/o text into the buffer, interspersed with input regions. Joël> Does mmm-mode can be used in this case ? If you have a mode which parses the buffer for you, such as mmm mode, and exposes the extents, overlays, or regions to other Lisp programs, you just figure out which extents [regions] should be readonly and set the readonly text property there using `(set-extent-property extent 'read-only t)' [`(add-text-properties start end '(read-only t))']. You could also have a trivial `read-only' mode which makes the whole buffer read-only, and use mmm-mode (in fact, you could just put `toggle-read-only' on mmm-mode's hooks I suspect), but this could have surprising results. For example, it is possible to write functions which change arbitrary regions of text (ie, not containing point) without moving point. With this strategy, such functions would work just as well on "read-only" regions as long as point is in a read-write region. -- Institute of Policy and Planning Sciences http://turnbull.sk.tsukuba.ac.jp University of Tsukuba Tennodai 1-1-1 Tsukuba 305-8573 JAPAN My nostalgia for Icon makes me forget about any of the bad things. I don't have much nostalgia for Perl, so its faults I remember. Scott Gilbert c.l.py