anchor.diff:  
   (defun get-window-monitor (&optional (window *window*))
     (let ((monitor (%glfw:get-window-monitor window)))
  -    (unless (eq monitor (cffi:null-pointer))
  +    (unless (cffi:null-pointer-p monitor)
         monitor)))
   
   (defun get-window-attribute (attribute &optional (window *window*))
  
positive.code:   "Wrap BODY with an initialized GLFW instance, ensuring proper termination. If no error callback is set when this is called, a default error callback is set."
    `(progn
       (let ((prev-error-fun (set-error-callback 'default-error-fun)))
         (unless (eq prev-error-fun (cffi:null-pointer))
  	 (%glfw:set-error-callback prev-error-fun)))
       (initialize)
       (unwind-protect (progn ,@body)
  
negative.code:      (opengl-debug-context :boolean)
       (opengl-profile '%glfw::opengl-profile)))
    (let ((window (%glfw:create-window width height title monitor shared)))
      (if (cffi:null-pointer-p window)
  	(error "Error creating window.")
  	(make-context-current window))))
  
  