The members of our community have repeatedly asked if modal pop-ups are possible - they don't like the current functionality of clicking an image and it opens an entirely new tab. They have even lost posts because of our use of the full editor and them followed images added to the OP's post during their reply (I believe, from limited testing this is resolved in v9 with the latest TinyMCE version as it saves the body of the post). Still the user should not be taken away from there post when re-checking a screenshot during a reply.
We could implement modal pop-ups with a customization but I'm finding the more we customize the more the site becomes fragile with major/minor releases. Plus modal pop-ups are a extremely common way to view images and in some sense, anything else is old-fashioned and lagging behind.
It would be great to have this modern way to view images and certain attachments like video on threads (at least) but also across all site's applications in a modal pop up. Example: http://www.w3schools.com/howto/howto_css_modals.asp