anchor.diff:             (ds (text-style-descent (pane-text-style gadget) gadget))
              (w  (+ (text-size gadget label :text-style (pane-text-style gadget)) wider))
              (h  (+ as ds higher)))
  -      (make-space-requirement :width w  :min-width w  :max-width  w
  -                              :height h :min-height h :max-height h))))
  +      (make-space-requirement :width w  :min-width w  :max-width  +fill+
  +                              :height h :min-height h :max-height +fill+))))
   
   (defgeneric draw-label* (pane x1 y1 x2 y2 &key ink))
   
  
positive.code:      (space-requirement+* sr
                            :min-width  (* 3 (pane-x-spacing pane))
                            :width      (* 3 (pane-x-spacing pane))
                            :max-width  (* 3 (pane-x-spacing pane))
                            :min-height (* 2 (pane-y-spacing pane))
                            :height     (* 2 (pane-y-spacing pane))
                            :max-height (* 2 (pane-y-spacing pane)))
       :min-width (space-requirement-height sr)
       :width     (space-requirement-height sr)
       :max-width (space-requirement-height sr)
       :min-height 0
       :max-height 0
       :height 0)))
  
  (defgeneric draw-toggle-button-indicator (gadget type value x1 y1 x2 y2))
  
negative.code:   (space-requirement+* (space-requirement+* (compose-label-space gadget)
                                              :min-width (* 2 (pane-x-spacing gadget))
                                              :width (* 2 (pane-x-spacing gadget))
                                              :max-width +fill+
                                              :min-height (* 2 (pane-y-spacing gadget))
                                              :height (* 2 (pane-y-spacing gadget))
                                              :max-height +fill+)
                         :min-width (* 2 *3d-border-thickness*)
                         :width (* 2 *3d-border-thickness*)
                         :min-height (* 2 *3d-border-thickness*)
                         :height (* 2 *3d-border-thickness*)))
  
  ;;; ------------------------------------------------------------------------------------------
  ;;;  30.4.4 The concrete scroll-bar Gadget
  