ZeroEditor-> press F11
You are now in decal edit mode.
I'm not sure what exactly it was supposed to do, especially since decalls where taken out... maybe printing a new texture over the existing ones. And I bet this is unsupported and is not working properly. But it sounds cool to me...

RC-1290'Dreadnought'

I did that by accident yesterday. Had no idea what it was. I still don't know what it's suppose to do. Sounds cool to me though. And I agree about the no doubt that it is unsupported.