Texture weight painting mode does it work?

Iam using Unreal engine v 4.17 which has three paint options under the paint mode viz Colours, Weights and Textures. Ive managed to get colours and vertex weighting painting to work on my static mesh but am at a complete loss how to texture weight paint.

The documentation is outdated which doesnt help much. Anyone figured out how this works?

I had a try Alis_0_1_9 - Unreal Editor (574 kb) закачан 13 января 2018 г. Joxi

you choose texture on which you want to paint and color, next the same