Ardour’s ability to import external media files remains essentially unchanged in version 3.0, but thanks to work by Sakari Bergen, an entirely new kind of import is now possible: importing specific material from another session.
Session->Import From Session …, this process is driven via a dialog that allows to select an existing session file or snapshot (basically any file ending in “.ardour”). It then presents a list of elements that can be imported: Regions, Tracks, Playlists, Locations, and the tempo map.
You can select any, all or none of the elements to bring into the current session. Regions will end up in the region list. Tracks will appear as new tracks. Locations will be added to the relevant ruler bars and the locations dialog. Playlists will become available via track playlist selector buttons. The tempo map will replace the existing tempo map.
Note that at present, this feature is not working correctly, and it is possible (though not likely) that we may hide of the alpha release of 3.0. It will be back before a final release, however