Individual Vertex coloring in SceneWdget (with Open3DScene) like the one in Visualizer or visualization::DrawGeometries

[PiotrRyw]

Edit. There is a proper coloring in Open3DScene; incorrect data was being loaded to Open3DScene while correct data to DrawGeometries.

I have a point cloud object with assigned colors (based on some important property) and I need to display those (individual!) vertex colors in the GUI I've made using Open3D tools.
The point cloud object is being properly displayed by the visualization::DrawGeometries() function, but the Open3DScene in the SceneWidget of my GUI still displays a solid color, as defined in the default MaterialRecord struct.

I do not see how to set up the rendering::MaterialRecord so that it colors each vertex by a different color. How to achieve that result?