anchor.diff:        (gl:load-identity)
         (gl:clear-color 0.0 0.0 1.0 1.0)
         (gl:clear :color-buffer)
  +
  +      ;; open any game controllers
  +      (loop for i from 0 upto (- (sdl2:joystick-count) 1)
  +         do (when (sdl2:game-controller-p i)
  +              (setf controllers (acons i (sdl2:game-controller-open i) controllers))))
  +      
         (sdl2:with-event-loop (:method :poll)
           (:keydown (:keysym keysym)
             (let ((scancode (sdl2:scancode-value keysym))
  
positive.code:           (gl:flush)
            (sdl2:gl-swap-window win))
          (:quit () t))
        (sdl2:gl-delete-context gl-context)
        (sdl2:destroy-window win))))
  
negative.code: (require :cl-opengl)
  
  (defun basic-test ()
    (sdl2:with-init (:everything)
      (let* ((win (sdl2:create-window :flags '(:shown :opengl)))
             (gl-context (sdl2:gl-create-context win))
             (controllers ()))
  
        ;; basic window/gl setup
        (sdl2:gl-make-current win gl-context)
        (gl:viewport 0 0 800 600)
        (gl:matrix-mode :projection)
  