As a user who doesn’t have access to our forum’s settings, I was doing some testing to see if there was a cap on how many people we could add to a PM at once. I ended up adding a bunch of inactive accounts to the PM, but in the end it got pretty annoying to scroll through that list of users to get to the reply area. Here’s a screenshot of how bad it got:
Of course, this extreme amount of participants is an edge case, but even with only two to three rows (6 to 11 users) participating in a PM, I can see that list getting annoying. The collapse button should hide the list of users. Currently it only toggles between condensed/expanded view for Frequent Posters.