The few docs we have are on our development.saphirion.com web-site. And yes, R3-GUI targets something different then VID or Carl's idea. It's for long-maintenance, business applications. So, not for a quick & dirty approach.
I don't know how often I explained this... If you expect a VID on R3 don't use R3-GUI, it's for full-blown applications.
I am not sure it differs much to what Carl prototyped? All R3 GUIs are light years ahead from VID, conceptually ....
I am just skimming thru the Windows 10 universal apps. They have even a Git repo for that. The world is still insane - tonnes of XMLs. If Red wants to link to that natively, not sure yet, how to do it. Most probably generate via some templates.
"It's for long-maintenance, business applications" Can you elaborate more on that? What are the features that makes it more suitable for business applications?
What Robert means is, that no all R3 GUI concepts are easy, but they are flexible to build "whatever" app you envision.
basic gui elements, plus events, chaining, updates, resizing ...
I never had much trouble building any app I envisioned with R2/VID, it was flexible-enough to me.
R3-GUI was developed in a purpose driven manner with some specific apps in mind. That's why for example the table widget is rather complex, because the app needed said features for the table.
also there's some support directly in layout to connect forms to databases.
We had a few resizing libraries since more than a decade for R2, just not included by default in the View distro. I even wrote my own one and used it in many apps.
I really liked Carl's demo - simple, elegant, juicy colors ... and I am still admiring, how VID code could look nice ... You can give it a try, just type - demo