Multi-Biome Map? Also, Allow Paint Terrain Brushes outside their Biomes?

So.
Let's say you're on the Jungle Biome, and you wanna make a transition into the Desert Biome.
As i understand for now, the terrain paint brushes, are tied to the Biome the map is in.

Maybe, adding the option to have "Multi-Biome" to allow us to have the paint brushes of multiple Biomes?
So we can make transition maps!

Of course for Map Generation, you choose one of the Multi-Biomes as the "Source Biome" of course, and when you start to expand the map, you may get a prompt "What biome generate the extension"

This would allow us to create some amazing mixture of biomes, and allow us to have access to more Paint Terrain Brushes outside of their original Biomes.

Lastly, like the water, could we see a "Name" for each kind of Paint Terrain?