There are some difference between reviewed and unreviewed files on the left changed files tree.

[lunny]

When I want to have a glance for all unreviewed files, I want to take a look at the changed file tree. But there is no any difference between reviewed and unreviewed files on the left changed files tree.

[delvh]

I think I mentioned something similar once already:
I think it would be best to get rid of the "useless" file icon in the tree, and replace it with a readonly checkbox which file is already viewed.
We can even think about using indeterminate for files that have changed in the meantime.
That way, we don't need additional space but display more information.
The only problem is keeping the checkboxes in sync with the actual files.

[lunny]

How about using different colors for viewed and unviewed files.