Does canvas-diagram support PathGradientBrush or RadialGradientBrush  for setBackBrush() ?
The help shows:
var gradientBrush = { type: "LinearGradientBrush", color1: "green", color2: "white", angle: 30 };
Is there any documentation on how to create other gradientBrushes?
When I try this the diagram does not generate an eroor, but the backcolor turns black:
var gradientBrush = { type: "RadialGradientBrush", color1: "green", color2: "white" };

This version lets you use radial gradients:
https://mindfusion.eu/_beta/jsdiag_radial.zip

For example:

var brush1 = { type: "RadialGradientBrush", color1: '#8ED6FF', color2: '#004CB3' };

var brush2 ...
brush2.colorStops = [
  { position: 0, color: 'red'},
  { position: 0.5, color: 'blue' },
  { position: 1, color: 'green' },
] 

We'll implement some conversion between them and .NET's path graidents for the NetDiagram 5 release.

I hope that helps,
Stoyan