The value returned by current-local-map for the minibuffer seems to be
wrong (both in the trunk and in Emacs 22.1), containing partial
reduplication:

(keymap
 (C-tab . file-cache-minibuffer-complete)
 (10 . minibuffer-complete-and-exit)
 (13 . minibuffer-complete-and-exit)
 keymap
 (menu-bar keymap
	   (minibuf "Minibuf" keymap
		    (tab menu-item "Complete" minibuffer-complete
			 ([9]
			  . "  (TAB)")
			 :help "Complete as far as possible")
		    (space menu-item "Complete Word" minibuffer-complete-word
			   ([32]
			    . "  (SPC)")
			   :help "Complete at most one word")
		    (63 menu-item "List Completions" minibuffer-completion-help
			([63]
			 . "  (?)")
			:help "Display all possible completions")
		    "Minibuf" keymap
		    (return menu-item "Enter" exit-minibuffer
			    (nil)
			    :help "Terminate input and exit minibuffer")
		    (quit menu-item "Quit" keyboard-escape-quit
			  ([134217755 27]
			   . "  (M-ESC ESC)")
			  :help "Abort input and exit minibuffer")
		    "Minibuf")
	   keymap
	   (minibuf "Minibuf" keymap
		    (return menu-item "Enter" exit-minibuffer
			    (nil)
			    :help "Terminate input and exit minibuffer")
		    (quit menu-item "Quit" keyboard-escape-quit
			  ([134217755 27]
			   . "  (M-ESC ESC)")
			  :help "Abort input and exit minibuffer")
		    "Minibuf"))
 (27 keymap
     (118 . switch-to-completions)
     keymap
     (114 . previous-matching-history-element)
     (115 . next-matching-history-element)
     (112 . previous-history-element)
     (110 . next-history-element))
 (prior . switch-to-completions)
 (C-tab . file-cache-minibuffer-complete)
 (63 . minibuffer-completion-help)
 (32 . minibuffer-complete-word)
 (9 . minibuffer-complete)
 keymap
 (menu-bar keymap
	   (minibuf "Minibuf" keymap
		    (return menu-item "Enter" exit-minibuffer
			    (nil)
			    :help "Terminate input and exit minibuffer")
		    (quit menu-item "Quit" keyboard-escape-quit
			  ([134217755 27]
			   . "  (M-ESC ESC)")
			  :help "Abort input and exit minibuffer")
		    "Minibuf"))
 (C-tab . file-cache-minibuffer-complete)
 (9 . self-insert-command)
 (up . previous-history-element)
 (prior . previous-history-element)
 (down . next-history-element)
 (next . next-history-element)
 (27 keymap
     (114 . previous-matching-history-element)
     (115 . next-matching-history-element)
     (112 . previous-history-element)
     (110 . next-history-element))
 (10 . exit-minibuffer)
 (13 . exit-minibuffer)
 (7 . abort-recursive-edit))

As a result of this, typing <C-down-mouse-3> in the minibuffer pops up a
confusing context menu, see the attached screen shots.

Steve Berman