gtk: fix over-eager attempt at alt- menu activation

Closes PR 11843

original commit: aabd5f7bd2e0b71ad218f9f0475abcd64e4b9afa

collects/mred/private/wx/gtk/menu-bar.rkt

@@ -145,4 +145,16 @@
          (g_object_ref gtk)
          (gtk_menu_item_set_submenu item gtk))
        (gtk_menu_shell_append gtk item)
-       (gtk_widget_show item)))))
+       (gtk_widget_show item))))
+
+  (define/public (activate-item menu)
+    ;; Gtk takes care of menu activation as appropriate;
+    ;; return #f to indcate that the key wasn't handled
+    #f
+    #;
+    (let loop ([menus menus])
+      (cond
+       [(null? menus) (void)]
+       [(eq? menu (cadar menus))
+	(gtk_menu_shell_select_item gtk (caar menus))]
+       [else (loop (cdr menus))]))))

collects/mred/private/wx/gtk/menu.rkt

@@ -237,7 +237,9 @@
        (gtk_menu_shell_append gtk item-gtk)
        (gtk_widget_show item-gtk))))
 
-  (def/public-unimplemented select)
+  (define/public (select bm)
+    (send parent activate-item this))
+
   (def/public-unimplemented get-font)
   (def/public-unimplemented set-width)
   (def/public-unimplemented set-title)

collects/mred/private/wx/win32/menu.rkt

@@ -53,7 +53,8 @@
     (when parent
       (let ([m (regexp-match #rx"&[^&]" label)])
         (when m
-          (send parent popup-menu-with-char (string-ref (car m) 1))))))
+          (send parent popup-menu-with-char (string-ref (car m) 1)))))
+    #t)
 
   (def/public-unimplemented get-font)
   (def/public-unimplemented set-width)

collects/mred/private/wxmenu.rkt

@@ -68,9 +68,7 @@
 						     [label (mcar data)]
 						     [menu (mcdr data)])
 						(if (regexp-match re label)
-						    (begin
-						      (send menu select this)
-						      #t)
+						    (send menu select this)
 						    #f)))
 					    items)))))))))]
 	[on-demand (lambda () (as-exit (lambda () (send mred on-demand))))]