Looks like default-off (phew), unlike Chrome. A feature no-one asked for. Especially in FF where memory is well managed.

I have longed for this feature. For me, it is useful in many scenarios, such as:

  * reading two distantly separated sections of a long article on two split tabs;
  * reading a research paper on one tab and typing a question to StackExchange on the other;
  * reading a scanned book written in French on one tab and using a dictionary on the other.

I never thought I'd say something nice about Google Chrome, but this feature was the only reason that I sometimes used that browser instead of Firefox. The split view is incredibly handy when you're looking at a web application and an observability tool for that web application at the same time.

I might not have asked for it (because it never occurred to me) but I'm actually interested in trying it.