In 2.8 we added the ability to bring multiple objects into Edit Mode. However, it’s not easy enough to pull in more objects into the Edit Mode session, or to evict items from it. The Outliner can be of great use here. Here’s how I think we can solve it:
When in Edit Mode (or any mode that supports editing multiple objects), we add a fourth column of toggles. Using these, it’s easily possible to either add in any items into your session, or to evict something you are done editing.
As a bonus, the also makes it easier to see which items are in the mode and which are not.