var g = NewGraph2D( { BorderWidth: 5, DrawFunc: test } );

function test(g) {
  g.SetWindowWH( 0, 0, 600, 400 );
  var grad = g.CreateRadialGradient( {
    X1: 200, Y1: 100, R1: 0, X2: 400, Y2: 100, R2: 300,
    Stops: [
      { Pos: 0, Color: 'rgb(0,0,255)' },
      { Pos: 1, Color: 'rgb(255,255,0)' }
    ]
  } );
  g.SetBgColor( grad );
  g.RectWH( 0, 0, 600, 200, 2 );
  g.SetRadialGradientGeom( grad, { Y1: 300, Y2: 300 } );
  g.Ellipse( 300, 300, 300, 100, 0, 2 );
}