add is-function-added? is keymap%

original commit: fbb16de87131d6a1705288de55c529baa32b8eaa

pkgs/gui-pkgs/gui-doc/scribblings/gui/keymap-class.scrbl

@@ -50,6 +50,14 @@ When the function is called, it gets the arguments that were passed to
 
 }
 
+@defmethod[(is-function-added? [fname string?]) boolean?]{
+  Returns @racket[#t] if @racket[fname] has been added
+          via @method[add-function keymap%] to this keymap 
+          and @racket[#f] otherwise.
+
+  This method doesn't check chained keymaps to see if the function
+  has been added to one of those.
+}
 
 @defmethod[(break-sequence)
            void?]{
@@ -339,8 +347,7 @@ A function name does not have to be mapped to a handler before input
  function names.
 
 }
-
-
+                 
 @defmethod[(remove-chained-keymap [keymap (is-a?/c keymap%)])
            void?]{
 

pkgs/gui-pkgs/gui-lib/mred/private/wxme/keymap.rkt

@@ -720,6 +720,9 @@
                chain-to)]
        [else
         (error 'keymap "no function ~e" name)])))
+  
+  (def/public (is-function-added? [string? name])
+    (and (hash-ref functions name #f) #t))
 
   (def/public (get-double-click-interval)
     double-interval)