Feature request: Using segments/lists to create new segments

It’s my understanding that Lists and Segments are essentially the same under the hood. When sending to lists or segments, the recipients are the union of both sets of subscribers.

I would love to see functionality in the Segments section that allows for creation of new segments as the union or intersection of other segment filters. For example:

Subscribers who are:
– Members of of list X AND
– Have a user role of Y AND
– Have opened Newsletter Z

When sending a Newsletter, it would also be useful to be able to choose whether the recipients should be members of ANY of the selected lists or ALL of the selected lists. This would address the use case above by making it possible to filter the recipient list, even if it doesn’t result in a new segment.

Thanks for your consideration.