This is in the responsive site only.

As a GM, in my private messages area I have a bunch of threads titled "Access to <game name>."  It is early in the game and we are still discussing some of the character traits, backstories, etc. so I am still using all of those threads.  I found it was difficult to figure out which was the thread I wanted, so I thought I would change the thread title to be the character name.

While the 'Edit Thread' button is there in the Private Messages screen, it does not edit that thread, but (I guess) whatever thread it thinks it has selected on the primary game screen.  In the old site, there isn't even an 'Edit Thread' button in the PM screen, so this issue doesn't come up.