(defvar calendar-mouse-3-map (make-sparse-keymap "Calendar"))
(define-key calendar-mode-map [down-mouse-3] calendar-mouse-3-map)
+(define-key calendar-mode-map [C-down-mouse-3] calendar-mouse-3-map)
(define-key calendar-mode-map [menu-bar moon]
(cons "Moon" (make-sparse-keymap "Moon")))