when constructing SEARCH message, include time in the message as well. This will enable us to ignore any messages when we have a 'later' state available.

shell/search-thread.sml

@@ -5,7 +5,7 @@ struct
   (* Prerequisite to sending message: move buffer to end. *)
   fun loop (searchMailbox, inputMailbox) =
     let
-      val (buffer, searchString) = Mailbox.recv searchMailbox
+      val (buffer, searchString, time) = Mailbox.recv searchMailbox
       val searchList = SearchList.build (buffer, searchString)
       val () = Mailbox.send (inputMailbox, InputMsg.WITH_SEARCH_LIST searchList)
     in

shell/update-thread.sml

@@ -7,8 +7,8 @@ struct
   fun sendMsg (msg, drawMailbox, searchMailbox) =
     case msg of
       DRAW msg => Mailbox.send (drawMailbox, msg)
-    | SEARCH (buffer, searchString) =>
-        Mailbox.send (searchMailbox, (buffer, searchString))
+    | SEARCH (buffer, searchString, time) =>
+        Mailbox.send (searchMailbox, (buffer, searchString, time))
 
   fun sendMsgs (msgList, drawMailbox, searchMailbox) =
     case msgList of