R1:88b46063b431

Make durable column sticky across requests

Summary: When you open the column, keep it open on future requests.

Test Plan: Opened column, clicked to Conpherence (no column), clicked elsewhere (column again), reloaded page (column), closed column, clicked something (no column).

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: epriestley

Differential Revision: https://secure.phabricator.com/D12038