anchor.diff:              (c (stack-space-requirements-horizontally csrs)))
           (let ((res
                  (make-space-requirement
  -                :width (space-requirement-width r)
  -                :min-width (space-requirement-min-width r)
  -                :max-width (space-requirement-max-width r)
  -                :height (space-requirement-height c)
  +                :width      (space-requirement-width r)
  +                :min-width  (space-requirement-min-width r)
  +                :max-width  (space-requirement-max-width r)
  +                :height     (space-requirement-height c)
                   :min-height (space-requirement-min-height c)
                   :max-height (space-requirement-max-height c))))
             #+NIL
  
positive.code:             ;; ^- this can't be true...
              ;;    the user should only be able to win within the pane's min-max
              (when user-foo
                (setf foo (spacing-value-to-device-units pane user-foo)))
              ;;
              (setf min-foo
                (clamp
  
negative.code: 
        (dada ((foo width height))
              ;; the user wins on the "primary" dimensions
              (when user-foo
                (setf foo (spacing-value-to-device-units pane user-foo)))
              ;;
  