My apologies, if any are needed, for replying to a two-year-old post. I just discovered this function today by accident. (I’ve had Scrivener since July 2021. eep!) Anyway, I am working on a short story that is a part of a much larger storyverse and I needed to look up something in the series’ ‘bible,’ which is mostly in the binder of a novel in said universe. Up until ten minutes ago, separate windows would open, one for each project and I would have to manually switch back and forth between windows. However, I see that the novel opened in another tab of the short story project. I came here with the intent of asking “Since when has this been possible?” since I heard that tab functions were disabled by Apple. But the forum told me my question was similar to others, and this was the best one.
This is really helpful (both the multiple projects in tabs in one window and the forum seeing a potentially redundant topic.)
I must have accidentally selected the ‘merge all windows’ command at some point recently.