What version are you running?
2.5.2
What's the URL of the page this enhancement relates to, if any?
.../r/####/diff/#
Describe the enhancement and the motivation for it.
Add some form of UI which shows the current file header in the diff viewer while you scroll - allowing you to quickly check which file you're looking at.
There are many ways this could be accomplished, possibly with position:sticky, etc.
Please provide any additional information below.
First reported as a desired feature of MozReview (Mozilla's customized Review Board instance) here: https://bugzilla.mozilla.org/show_bug.cgi?id=1203969