anchor.diff:  
   (defvar *display* (open-default-display))
   (defvar *root* (screen-root (display-default-screen *display*)))
  -(defparameter *windows* nil "List of managed windows.")
  +(defparameter *windows* nil "List of managed and mapped windows.")
   (defparameter *last* nil "Last focused window.")
   (defparameter *curr* nil "Current focused window.")
   
  
positive.code:                                 (string= class "MuPDF"))))
    "List of predicates against which windows are grouped")
  
  (defun add (window)
    "Add window to the list of managed windows. Take care of grouping
  and don't add window already in the list."
    (let ((grouper (find-if #'(lambda (f) (funcall f window)) *groupers*)))
  
negative.code:                (:map-notify
                  (window override-redirect-p)
                  (unless override-redirect-p
                    (focus (plus window))))
                 (:unmap-notify
                  (window)
                  (focus (minus window)))))
        (ungrab-button *root* (code *move*) :modifiers (state *move*))
        (ungrab-button *root* (code *resize*) :modifiers (state *resize*))
        (ungrab-button *root* (code *kill*) :modifiers (state *kill*))
  