anchor.diff:      (let ((frame (make-frame (current-frame))))
         (setup-frame frame (primordial-buffer))
         (allocate-frame vf frame)
  -      (switch-current-frame vf frame)
  -      (setf (virtual-frame-changed vf) t))))
  +      (switch-current-frame vf frame))))
   
   (define-key *global-keymap* "C-z d" 'frame-multiplexer-delete)
   (define-command frame-multiplexer-delete () ()
  
positive.code:          (frame (search-next-frame vf (virtual-frame-current vf))))
      (when frame
        (switch-current-frame vf frame))
      (lem::change-display-size-hook)
      (setf (virtual-frame-changed vf) t)))
  
  (define-command frame-multiplexer-test () ()
    (labels ((vf ()
  
negative.code: 
  (defun switch-current-frame (virtual-frame frame)
    (setf (virtual-frame-current virtual-frame) frame)
    (setf (virtual-frame-changed virtual-frame) t)
    (map-frame (implementation) frame))
  
  (defun find-unused-frame-id (virtual-frame)
  