Review merge requests changes with a file tree
Description
One of the things that I have grown to appreciate while using Phabricator's code review tool is the file tree view that (optionally) sits to the left of the diff. Not only does this provide a high-level outline of the structure of the patch, but it also updates to reflect one's current location. Our project typically sees rather large patches on large source files, so this view provides an easy way to orient oneself during review.
Proposal
It's not entirely clear how concept would fit into GitLab's current patch view, which is already rather horizontally constrained due to the left and right sidebars. In my opinion the left sidebar has little value during review; perhaps allow the user to hide it in favor of a file tree?
Links / references
Edited by James Ramsay (ex-GitLab)