anchor.diff:    (call-next-method)
     (%list-store-set-column-types list-store column-types)
     (when column-names
  -    (setf (object-data list-store 'column-names) column-names))
  +    (setf 
  +     (object-data list-store 'column-names) 
  +     (coerce column-names 'vector)))
     (when initial-content
       (loop
        with iter = (make-instance 'tree-iter)
  
positive.code:   (column int)
    (gvalue gvalue))
  
  (defun tree-model-value (model row column)
    (let ((index (column-index model column))
  	(iter (etypecase row
  		(tree-iter row)
  
negative.code: 			 (funcall setter value iter))
  		 row setters)))))))
  
  (defgeneric (setf tree-model-value) (value model row column))
  
  (defmethod (setf tree-model-value) (value (model tree-model) row column)
    (let ((iter (etypecase row
  		(tree-iter row)
  		(tree-path (multiple-value-bind (valid iter)
  