anchor.diff:    (format t "GL renderer: ~a~%" (gl:get* :renderer))
     (format t "GL extensions: ~a~%" (gl:get* :extensions))
   
  -  (loop for i in '(:max-3d-texture-size
  +  (loop for i in '(:max-clip-planes
  +                   :max-clip-distances
  +                   :max-3d-texture-size
                      :max-texture-size
                      :max-array-texture-layers
                      :max-texture-lod-bias
  
positive.code:   (:default-initargs :width 500 :height 500 :title "gl-info.lisp"
                       :mode '(:double :rgba)))
  
  (defmethod glut:display-window :before ((w gl-info-window))
    ;; todo: check for extensions/versions before some of these...
    (format t "GL version: ~a~%" (gl:get* :version))
  
negative.code:                    :max-list-nesting
                     :max-eval-order
                     :max-viewport-dims
                     :max-viewports
                     :viewport-subpixel-bits
                     :viewport-bounds-range
                     :max-attrib-stack-depth
                     :max-client-attrib-stack-depth
                     :aliased-point-size-range
  