You still can't do a search with origin from multiple countries, which annoys me. If I want to find the cheapest ticket for a cross-atlantic trip, it would be very helpful to have such a feature.
Kiwi used to have this in their map view -- you could select a very large circular region regardless of country as the origin -- but it seems like they got rid of it.
This was by far the most useful tool to identify cheap segments and cut down the space of options.
You used to be able to. It was brilliant, you could do a quick relocation flight, even make it a nice little first stop, and then get a nice long haul somewhere else.