You can find some additional information about VID here: http://www.red-by-example.org/vid.html.
Much more info about the drawing dialect can be found here: http://www.red-by-example.org/draw.html .
Official docs about the GUI system are, for the time being, rather formal and can be found here: https://doc.red-lang.org/en/gui.html. It includes in-depth info about the View engine, VID, and the draw dialect.