Configuration option to enable/disable showing all mail accounts in navigation sidebar

In previous versions of Mailbird only a single mailbox (account) appeared at the top of the navigation sidebar. Clicking on the account acted like a spring loaded pull down menu to select a different mailbox. With the sidebar redesign all configured accounts and the Unified mailbox show at the top of the navigation sidebar. This can use a significant amount of window real-estate when multiple accounts are configured.

Ideally this would be a configurable option in settings, allowing users to select their preferred display method.