cocoa: fix "&" handling in menu-item labels

Closes PR 12025

collects/mred/private/wx/cocoa/menu-item.rkt

@@ -61,7 +61,7 @@
         (send submenu install menu label enabled?)
         (let ([item (as-objc-allocation
                      (tell (tell MyMenuItem alloc) 
-                           initWithTitle: #:type _NSString (regexp-replace #rx"\t.*" label "")
+                           initWithTitle: #:type _NSString (clean-menu-label (regexp-replace #rx"\t.*" label ""))
                            action: #:type _SEL #f
                            keyEquivalent: #:type _NSString ""))])
           (set-ivar! item wxb (->wxb this))

collects/tests/gracket/item.rkt

@@ -266,6 +266,10 @@
 					 "[on-demand hook]"
 					 m
 					 void)
+			    (make-object menu-item%
+					 "6 && Half-D&ozen"
+					 m
+					 void)
 			    (let mloop ([m m][sub-at-50? #t])
 			      (let ([sm (if (and sub-at-50?
 						 (send e button-down? 'middle))
@@ -750,7 +754,8 @@
 			tab grp)]
 	   [canvas  (make-object popup-test-canvas% 
 				 items
-				 (list "h slider" "v slider"
+				 (list "combo"
+                                       "h slider" "v slider"
 				       "v gauge" "v gauge"
 				       ; "text msg" "image msg"
 				       "text"