In bug 878551, the ability to move the list-all-tabs button was removed for a few reasons: > Moving this widget to the navbar gives it a tiny scaled version of Toolbar.png (like a horizontal line). > Moving it back to the tab strip make it misbehave. It disappears, but sometimes flickers into view when opening/closing a tab. These issues are no longer present, so we should be able to allow moving the list-all-tabs button once again. Differential Revision: https://phabricator.services.mozilla.com/D224623