Index: stack.c
===================================================================
--- stack.c	(revision 549)
+++ stack.c	(working copy)
@@ -516,6 +516,8 @@ print_frame (struct frame_info *frame, i
   enum language funlang = language_unknown;
   struct ui_stream *stb;
   struct cleanup *old_chain, *list_chain;
+  struct frame_id this_frame_id;
+  char *frame_id_str = NULL;
 
   stb = ui_out_stream_new (uiout);
   old_chain = make_cleanup_ui_out_stream_delete (stb);
@@ -674,6 +676,16 @@ print_frame (struct frame_info *frame, i
 	}
     }
 
+  /* Print a string that represents the frame_id. This could be used by the UI
+     for comparison with the previous frame_id.  */
+  this_frame_id= get_frame_id (frame);
+  frame_id_str = xstrprintf ("%s,%s,%s",
+    (this_frame_id.stack_addr_p ? paddr (this_frame_id.stack_addr) : "!stack"),
+    (this_frame_id.code_addr_p ? paddr (this_frame_id.code_addr) : "!code"),
+    (this_frame_id.special_addr_p ? paddr (this_frame_id.special_addr) : "!special"));
+  ui_out_field_string (uiout, "frame_id", frame_id_str);
+  xfree (frame_id_str);
+
   /* do_cleanups will call ui_out_tuple_end() for us.  */
   do_cleanups (list_chain);
   ui_out_text (uiout, "\n");