anchor.diff:    (let ((sw (xlib:screen-width *screen*))
           (sh (xlib:screen-height *screen*)))
       (move *curr* :x 0 :y 0 :width sw :height sh)
  -    (when pinned-p (pin *curr*))))
  -
  -(defun center ()
  +    (when pinned-p (on :pinned *curr*))))
  +
  +(defun center (&key stay-centered-p)
     "Center the current window."
     (let ((sw (xlib:screen-width *screen*))
           (sh (xlib:screen-height *screen*))
           (w (xlib:drawable-width *curr*))
           (h (xlib:drawable-height *curr*)))
       (move *curr* :x (- (truncate sw 2) (truncate w 2))
  -                 :y (- (truncate sh 2) (truncate h 2)))))
  +                 :y (- (truncate sh 2) (truncate h 2)))
  +    (when stay-centered-p (on :centered *curr*))))
   
   (defun split-string (string &optional (character #\Space))
     "Returns a list of substrings of string
  
positive.code: (defshortcut (#\f) (fullscreen))
  (defshortcut (:shift #\f) (fullscreen :pinned-p t))
  (defshortcut (#\.) (center))
  (defshortcut (:shift #\.) (center))
  (defshortcut (:shift #\p) (toggle-pin))
  
  (defvar last-button nil)
  (defvar last-x nil)
  
negative.code:              (rplacd ,asc #',fn)
               (push (cons ,sc #',fn) *shortcuts*))))))
  
  (defun on-p (switch window) (getf (xlib:window-plist window) switch))
  (defun on (switch window) (setf (getf (xlib:window-plist window) switch) t))
  (defun off (switch window) (remf (xlib:window-plist window) switch))
  (defun toggle (switch window)
    (if (on-p switch window) (off switch window) (on switch window)))
  
  (defun correct-size (window &optional x y width height dx dy dw dh)
    "Correct a window's dimensions with its sizehints."
  