anchor.diff:    (setf (edition-screen-selection-boxes scr) '())
     (loop for i below (glaw:shape-nb-vertices (edition-screen-shape scr)) do
          (let ((box (glaw:create-bbox-from-shape (edition-screen-selection-shape scr))))
  -         (multiple-value-bind (x y z) (glaw:shape-get-vertex (edition-screen-shape scr) i)
  +         (multiple-value-bind (x y z) (glaw:shape-get-vertex/values (edition-screen-shape scr) i)
              (declare (ignore z))
              (multiple-value-bind (scr-x scr-y) (glaw:view-to-screen x y (edition-screen-view scr))
                (glaw:bbox-translate box scr-x scr-y)))
  
positive.code:   (loop for i in (edition-screen-creation-boxes it) do
         (glaw:render-bbox i))
    (glaw:set-color/rgb 1.0 1.0 1.0 1.0)
    (multiple-value-bind (x y z) (glaw:shape-get-vertex (edition-screen-shape it)
                                                        (edition-screen-selection it))
      (glaw:format-at 100 160 *font* "Selection: ~A;~A;~A" x y z)))
  
  
negative.code: 
  (defun edition-screen-translate-vertex (scr index dx dy)
    (let ((shape (edition-screen-shape scr)))
      (multiple-value-bind (x y z) (glaw:shape-get-vertex/values shape index)
        (glaw:shape-set-vertex shape index (+ x dx) (+ y dy) z)))
    (edition-screen-update-boxes scr))
  
  