A number of my users noted odd things with cursor movements, and I just encountered one myself. While I would love to have a shortcut-key for creating and leaving a comment box, this is not it.
In the attached screen capture, you can see I’m in a comment box, and while cursoring forward (to its end, or even backwards) the cursor escaped back over to the prose.
Thanks for reporting this. We know there are a few edge cases where this happens, but it’s very hard to reproduce, so it’s been hard to figure out exactly what’s going on and find a fix.
That said, we made some fixes this week addressing annotations and overall document stability that I think may fix the issue – or at minimum, throw an error when the edge case occurs. So, please let us know if you run into this again.