New GUI dynamically created from script

Hello Everyone

I decide to download new 4.6 Beta and try new GUI
It looks amazing but...

I should say it is extreme change into opposite direction. Before it was 100% depending on script, now it is fully drawable in Editor and I didn't find any examples of how to handle it from script.

I found latest documentation in: <install_dir>/Editor/Data/Documentation and there is a lot of explanation of how to draw elements in Editor, what each option mean and so on, also there is "Legacy GUI...

New GUI dynamically created from script