View Source Alternative
Here is an alternative screen mockup with a few more features. Is based on the same model (splitter bar with navigation on the left and source view on the right) however the navigation is also split so that review notes can be edited directly while reading the code.
The navigation area (top left) should include buttons for jumping to the previous / next diff {left} {right} and opening the previous next different file {Up} {Down}.
The navigation area should have some context menu items: Go to file (first diff), download file (or folder) especially important for jar files or encrypted files that do not expand in the tool, validate (maybe).
Underneath the full Review Edit Box should be visible so we can add our observations while reviewing the files / source code.
A bookmark button should insert current file name+line number into the review text for easy referral to code. For this the current line number has to be clicked (and thus, highlighted)
The File Contents pane should have additional features for compressing / expanding sections:
Changed (removed) code should also be collapsable with a special (yellow) button: