At times, but you can go back to alpha-3 any time. You can also try to just update the Terrain Editor but I guess it will fail (if not at install then when it tries to use terrain stuff thats not there yet).
I don’t understand… The nightly build comes without editor? I downloaded it and the executable is the test application, plus there are library jars… No editor!
I am working on a newer version with painting, it should be ready next week. It should also be more stable and allow for a lot more modification of the terrain.