(defcustom mouse-avoidance-mode nil
"Activate mouse avoidance mode.
See function `mouse-avoidance-mode' for possible values.
-This variable should be set only with \\[customize], which is equivalent
-to using the function `mouse-avoidance-mode'."
+Setting this variable directly does not take effect;
+use either \\[customize] or the function `mouse-avoidance-mode'."
:set (lambda (symbol value)
;; 'none below prevents toggling when value is nil.
(mouse-avoidance-mode (or value 'none)))