Marking a subforum read now takes a long time and takes you back to the main page when done. Using Firefox 57, 64 bit. Not sure if this was intentional, but just noticed this behavior this morning.
From the main index page, I usually right click and choose 'open link in new tab' and then double click the green INGO logo to change it to grey (marking the sub-forum as read). This recently changed refresh the page as well.
In the Advertisers and Marketplace forums, double clicking on a yellow balloon to mark it as read will take you away from the main index page to a page containing only the advertisers or marketplace subforums.
Both of these actions are annoying...Thanks for looking into this.