When I need to copy the link of the thumbnail, I would right click to tab the page of the browser in order to access the address bar.

How were you doing before? Did you do a simply click and after copy the address go back to the page?
Otherwise you can still right click on the thumbnail and chose "copy link" (or "copy target" or something like that, depending on the browsers), as before. Even with the added javascript popup the link at HTML level as not changed.
Or just right click on the enlarged image displayed in the popup and chose "copy image link".
I could easily add a "copy link" button in the popup, if it is handy.

By the way, earlier today I fixed a small bug: the edited comments were always included in the "Last edit: ..." mention the username, but the username is supposed to appear there only when edited by someone else (an admin).