JNGP?
Just downloaded it now, gonna give it shothttp://www.hiveworkshop.com/threads/jass-new-gen-pack.279576/
There is an edit tileset option.
Every map maker should be using this tool.
This is because it only modifies the terrain mesh. Tile buildability/pathing is a virtual relation in World Edit that it bakes certain pathing onto the pathing map over certain tile types. Like wise World Edit bakes all terrain, doodads and destructables into a mini-map image in the form of a JPEG BLP with no mipmaps which the game uses as the minimap image.Notice, though, that it won't change terrain properties like buildable/unbuildable, even though it can place buildable tiles on top of the unbuildable and the other way round, and it won't change the minimap terrain colour of the area it is applied to.