Hi,
Which version of the control are you using? ShapeLibrary was introduced in v.2.5 and is present both in the trial and licensed versions. If you're using the latest version, make sure that the browser is not serving an older cached versions of the script files.
In order to use the custom shape, its definition needs to be loaded in advance. You can also not rely on a xml file, but use the Shape class constructor to supply the shape definition. The above shape can be recreated in javascript like this:
var shape = new MindFusion.Diagramming.Shape({
id: "DoubleEllipse",
outline: "M100,50 A50,50,0,1,1,0,50 A50,50,0,1,1,100,50",
decoration: "M98,50 A48,48,0,1,1,2,50 A48,48,0,1,1,98,50",
fillMode: "nonzero"});
node.setShape(shape);
Regards,
Lyubo