Hmm, testing some more and comparing with Yacomo’s script, the variable declarations are on a different line in his script, which is apparently what throws the error. Not sure if it is intended behaviour.
I’m also trying to use setCropWindow which in DS3 was in DzRenderHandler, but I can’t see any working example apart from what you guys did in the Ambient Occlusion scripted render script, which however hides part of its declarations. If I use your property enumeration script on DzScriptedRenderer I get a very long list which from my perusal doesn’t seem to include setCropWindow. 
I know I must get the Handler (not enumerated either with your script), but the example in the DS3 documentation doesn’t work in DS4. I must say I’m feeling like one of those proverbial monkeys on a typewriter at this point… :-( Hmm and can the DzScriptedRenderer class be used in regular scripts that do not get run from the Scripted Renderer drop-down?
Here is one of the attempts I did, based on the DS3 getHandler script:
// Get the active viewport and camera
var oActiveView = MainWindow.getViewportMgr().getActiveViewport();
var oCamera = oActiveView.get3DViewport().getCamera();
// Get the render options
var oRenderOptions = App.getRenderMgr().getRenderOptions();
var RSize = new Size(600,600);
var oRect=Rect( 0.1,0.5,0.2,0.3 );
var RName="Render.jpg";
var On=1;
// Create a handler
var oHandler = DzRenderHandler.getHandler(RSize,0,RName );
// If we have a valid handler
if( oHandler ){
// Set the background color
DzScriptedRenderer.setUseCropWindow(On);
DzScriptedRenderer.setCropWindow( oRect );
// Get the renderer
var oRenderer = oRenderOptions.getActiveRenderer();
Render, using our handler and options
oRenderer.render( oHandler, oCamera, oRenderOptions );
}
Edit, BTW for anybody else who may be lurking, Rob’s property enumeration script can be found here
I hope I’ll have time to piece it this week!