anchor.diff:       (if (%glfw:init)
   	 (unwind-protect
   	      (progn
  -		(%glfw:set-error-callback *error-fun*)
   		,@body)
   	   (%glfw:terminate))
   	 (error "Error initializing glfw."))))
  
positive.code:    def-cursor-pos-callback
     def-cursor-enter-callback
     def-scroll-callback
     set-char-callback
     set-mouse-button-callback
     set-cursor-position-callback
  
negative.code:        ((,window :pointer) (,w :int) (,h :int))
       ,@body))
  
  (defun set-window-position-callback (callback-name &optional (window *window*))
    (%glfw:set-window-position-callback window (cffi:get-callback callback-name)))
  
  (defun set-window-size-callback (callback-name &optional (window *window*))
    (%glfw:set-window-size-callback window (cffi:get-callback callback-name)))
  
  (defun set-window-close-callback (callback-name &optional (window *window*))
    (%glfw:set-window-close-callback window (cffi:get-callback callback-name)))
  
  (defun set-window-focus-callback (callback-name &optional (window *window*))
    (%glfw:set-window-focus-callback window (cffi:get-callback callback-name)))
  
  (defun set-window-iconify-callback (callback-name &optional (window *window*))
    (%glfw:set-window-iconify-callback window (cffi:get-callback callback-name)))
  
  (defun set-framebuffer-size-callback (callback-name &optional (window *window*))
    (%glfw:set-framebuffer-size-callback window (cffi:get-callback callback-name)))
  
  ;;;; ## Events and input
  (import-export %glfw:poll-events %glfw:wait-events)
  