Highlight new comments on a file

[spocky]

When a file is invalidated, it's usual that the developer answers a comment.
Providing that you don't always have an active notification system (by email, jabber or whatever), tt might be an interesting feature to have a visual signal to highlight this information.

I can see this implemented in 2 different ways :
1- add another state to say "hey, please, check my comment", that has to be set manually
2- provide a new functionnality on the file list that highlights the files that have been changed since your last visit