There is no indicator for newly created texture layers in terrain layer window

Steps to Repro:
1. Open attached or create a new project
2. Hierarchy > right click
3. 3D object > terrain
4. Select paint texture from paint tab
5. Edit terrain layer > Add a layer
6. Create a new layer

Actual Result:
1. The layer get's selected automatically, however, any additional layers don't get selected when they are created
2. Layer comes by with an empty texture and there is no indicator for it, so it's hard to determine whether it's generated or not until it's manually selected. It may lead unused empty layers in the project if the user is using a lot of textures.

Expected result:
1. The newly created layer should have some indicator next to it or When a new layer is created it should automatically get selected

Occurring with:
2018.3.0a6 (13fac50c9eea) , 2018.3.0a5, 2018.3.0a4

Note:
New Terrain tools are introduced from alpha 2018.3.0a4

Environment:
Windows and Mac