anchor.diff:  
   (defdfun %next-event (window &key blocking)
     "Real next-event implementation."
  +  (declare (ignore window blocking))
     (error 'not-implemented))
   
   ;; method based event handling
  
positive.code:    Major and minor arguments specify the context version to use, when NIL
     (default value) old style gl context is created, otherwise framebuffer config
      based context creation is used."
    (error 'not-implemented))
  
  (defdfun destroy-window (window)
    "Destroy the provided GL window."
    (error 'not-implemented))
  
  (defdfun toggle-fullscreen (window)
    "Switch display resolution to WINDOW dimensions and make WINDOW fullscreen."
    (error 'not-implemented))
  
  (defdfun show-window (window)
    "Make WINDOW visible."
    (error 'not-implemented))
  
  (defdfun hide-window (window)
    "Make WINDOW not visible."
    (error 'not-implemented))
  
  (defdfun set-window-title (window title)
    "Set WINDOW title to TITLE."
    (error 'not-implemented))
  
  (defdfun swap-buffers (window)
    "Swaps GL buffers."
    (error 'not-implemented))
  
  ;;; Events handling
  
negative.code: ;; Default implementation
  (defdfun gl-get-proc-address (proc-name)
    "Get foreign pointer to the GL extension designed by PROC-NAME."
    (declare (ignore proc-name))
    (error 'not-implemented))
  
  (defdfun create-gl-context (window &key make-current major minor)
    "Creates a new OpenGL context of the specified version for the provided window
     and optionally make it current. If major and minor are NIL old style context creation is
     used."
    (declare (ignore window make-current major minor))
    (error 'not-implemented))
  
  (defdfun destroy-gl-context (ctx)
    "Detach and release the provided OpenGL context."
    (declare (ignore ctx))
    (error 'not-implemented))
  
  (defdfun attach-gl-context (window ctx)
    "Makes CTX the current OpenGL context and attach it to WINDOW."
    (declare (ignore window ctx))
    (error 'not-implemented))
  
  (defdfun detach-gl-context (ctx)
    "Make the provided OpenGL context no longer current."
    (declare (ignore ctx))
    (error 'not-implemented))
  
  (defdfun create-window (title width height &key major minor
  