"you can add any link (URL address) to your link menu thingie, including threads. But you can only bookmark threads or parts of threads or pages that have the little bookmark icon at the bottom right. Bookmarked pages have to be accessed through your profile "
Yes, what Joanna said.
and, if I'm understanding what you meant, Joanna -- I think it would be a great idea to be able to add a link by clicking on the "links" icon at the top right side of the page!
