[cells-devel] observers

[Andy Chambers]

Two questions...

1) What's the best way to remove an observer that's been set on some slot?

2) If there's an observer like

(defobserver image-files ((self widget))
  (loop for (name file-pathname) in (set-difference new-value
old-value :key 'car)
      do (tk-format `(:pre-make-tk  ,self)
           "image create photo ~(~a.~a~) -file {~a} -height ~a -width ~a"
           (^path) name (namestring file-pathname)
           (^height)(^width))))

....can I make one that specializes on a subclass of widget that
overrides the first?  How does one do this?

--
Andy