Often in a pull request, many issues are raised and it is difficult to figure out which ones have been resolved. It would be nice to put a workflow on a comment. In other words:

Marissa makes a comment on a line of code
Sergei fixes the problem, and pushes
Sergei marks the comment as resolved
Marissa verifies that the commit resolves the problem
Marissa marks the comment as closed

Also it would be good to allow Marissa to see which comments are still not resolved/closed yet.