anchor.diff:    (column int)
     (gvalue gvalue))
   
  -(defun tree-model-value (model row column)
  +(defgeneric tree-model-value (model row column))
  +
  +(defmethod tree-model-value ((model tree-model) row column)
     (let ((index (column-index model column))
   	(iter (etypecase row
   		(tree-iter row)
  
positive.code: ;; TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
  ;; SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  
  ;; $Id: gtktree.lisp,v 1.17 2006-02-28 16:33:39 espen Exp $
  
  
  (in-package "GTK")
  
negative.code:   (call-next-method)
    (%list-store-set-column-types list-store column-types)
    (when column-names
      (setf 
       (object-data list-store 'column-names) 
       (coerce column-names 'vector)))
    (when initial-content
      (loop
       with iter = (make-instance 'tree-iter)
  