Bug 1:
Consider an inbox with 3-4 or more pages of messages. Go to the second page, and archive at least a page worth of messages individually (so 20+) by opening the message and then hitting “Archive”. Hitting the “<” button to go back to the previous page will reload the same page that you were on, rather than going to the previous page.
Bug 2:
When you are on the last page of inbox/sent/archive, you can still click the “>” button and it will reload the frame, but obviously it won’t advance (because it can’t, it’s the last page) and stays on the last page. This does not happen for the “<” button at the first page.