Re: customize-face

[martin rudalics]

The bug seems related to the following change from 1997-06-20:

        (widget-after-change): Don't apply :notify here.
        (widget-before-change): New function.  Apply :notify here.

`widget-before-change' may modify text preceding the editable field.  As
a consequence FROM and TO values passed to `widget-after-change' get
messed up.  More precisely FROM is that of `widget-before-change' but TO
does account for the text change.  Inserting just one character may, for
example, pass a FROM value of 4378 and a TO value of 4436 giving the
illusion that I just inserted some 58 characters.

I suspect the change above was implemented to make undo work for
editable fields.  Permitting a before-change hook to modify a buffer,
however, seems asking for more trouble.  Moreover, undoing still doesn't
work reliably.  Finally, the bug will remove `widget-after-change' which
breaks the entire customization buffer.