Summary:
Ref T12733. Currently, we detect the changeset which is in the middle of the screen as the current changeset.
This doesn't always get us the most intuitive changeset, particularly after a navigation from the scroll objective list: when you jump to changeset "X", you'd tend to expect "X" to be shown in the header, but the //next// changeset may be shown if "X" is too short.
Instead, select the changeset near the top of the screen (spanning an invisible line slightly below the banner).
Test Plan: Scrolled and jumped through a document with long and short changesets, saw a more intuitive changeset selected by the banner.
Reviewers: chad
Reviewed By: chad
Maniphest Tasks: T12733
Differential Revision: https://secure.phabricator.com/D17976
ab80d3ef0c