anchor.diff:  (defvar *compositor-debug-enable* nil)
   
   (defvar *event-queue* (mezzano.sync:make-mailbox :name 'compositor-event-queue)
  -  "Internal FIFO used to submit events to the compositor.")
  +  "Internal mailbox used to submit events to the compositor.")
   
   (defun submit-compositor-event (event)
     (mezzano.sync:mailbox-send event *event-queue*))
  
positive.code:   ((%x :initarg :x :accessor window-x)
     (%y :initarg :y :accessor window-y)
     (%thread :initarg :thread :accessor window-thread)
     (%fifo :initarg :fifo :reader fifo)
     (%buffer :initarg :buffer :reader window-buffer)
     (%layer :initarg :layer :reader layer)
     (%subscribed-notifications :initarg :notifications :reader subscribed-notifications)
  
negative.code:       (push win *m-tab-list*))
      (expand-clip-rectangle-by-window win)))
  
  (defmacro with-window ((window mailbox width height &rest options) &body body)
    `(let (,window)
       (unwind-protect
            (progn (setf ,window (mezzano.gui.compositor:make-window ,mailbox ,width ,height ,@options))
                   ,@body)
         (when ,window
           (mezzano.gui.compositor:close-window ,window)))))
  
  (defun make-window (mailbox width height &key layer initial-z-order kind)
    (let ((window (make-instance 'window
                                 :mailbox mailbox
                                 :thread (mezzano.supervisor:current-thread)
                                 :buffer (mezzano.gui:make-surface width height)
                                 :layer layer
  