Under the "Mark Topic" button at the top and bottom of a thread you can bookmark the thread and do other things like this.
Thanks. Marked it. But it is not the same as I wished.
I want to mark a specific message and not the full topic which may have many messages. Also same for bookmark, i.e. a specific message is bookmarked for later perusal.
Anyway, this will do, till we have what I require. One more suggestion is to show text as "Mark Topic .." so that we get the idea it has something more. Now it looks like a button for one job.