Gmail has supported multiple inboxes for a long time already, and now Google wants to improve this mode significantly. It plans on adding independent scrolling and a unified toolbar for all of them, and wants to make the dual-pane view's width adjustable starting on February 20. The company also warns it'll remove the option to use a three-pane layout in conjunction with the preview pane, which could upset some people.
When you activate multiple inboxes, Gmail will show you various sections you can customize using search queries, which could help you get a better overview of your tasks, follow-ups, or any other categories you could ask for. At the moment, you toggle on this mode by heading to the gear icon in the top right corner of Gmail and then Settings -> Advanced. Once the update is live, these options will be moved to a more appropriate place in the Inbox tab under Inbox type.
Multiple inboxes' new place in Settings.
The new unified toolbar will make it easier to manipulate items in all inboxes at once — right now, each section has its own toolbar, so it's impossible to manage emails sprinkled across different places at the same time. Areas other than the primary inbox will also become collapsible altogether. In the two-pane view, both sides will get their own scrollbars, and the width of each will be adjustable by dragging the separator.
If you currently use both the preview pane and the right-pane multiple inbox layout, you'll be notified that this configuration is no longer supported. The section will be turned off automatically once the update reaches you. Additionally, the view will be renamed to "reading pane."
This toast will inform you about the deprecation when you use the preview pane in the two-column view.
The changes will roll out to first G Suite users on February 20 and will also come to people with personal Google Accounts. The company hasn't shared when exactly that will happen, but it'll likely follow a similar time frame.