The help screen describes the m key as "read/unread a post". I think the "m" key should be equivalent to clicking the "Mark as unread" button on the currently expanded post, but it is not. If I am viewing posts in list mode, and I open a post that is not the topmost one, and then I scroll all the way up using the mouse wheel, and then I press the m key, it will actually mark the topmost post as read even though I have not even opened it yet. Instead, I would expect that pressing the 'm' key should mark the opened post as unread in that situation.

This is very annoying for me because I have a habit of looking at a list of posts, opening one in the middle that looks interesting, and then discovering that it is too long to read right now so I want to mark it as unread. I would like to just press the 'm' key to do that, but I usually have to scroll all the way down to the bottom of the post and click "Mark as unread".

The only workaround is to just be careful about how I scroll. If I keep the opened post at the top of my screen, then the 'm' key seems to work correctly.