I just found an interesting feature.

In my junk mail folder, I highlight the email and I can click the button that says "Not Junk" and it does it's thing. BUT if I open the email, the button is "Junk" so I have to close the email to mark it as not junk.

I've only done this on a single message so far, but it could be a little confusing if someone wasn't paying much attention. So maybe an update could check to see the top level folder before picking the button.