RPCManager not opening up new window

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1. SmartGWT v9.0_2013-07-03/LGPL (Build 2013-07-03)

2. Firefox 8.0.1

I am trying to use RPCManager to send a request to a non-smartgwt server and have the response open up in a new window.

Here is my code
RPCRequest req = new RPCRequest();
req.setHttpMethod("POST");
req.setActionURL("https://www.myurl.com/myapp/showData?mydata=var1");
req.setUseSimpleHttp(Boolean.TRUE);
req.setDownlaodToNewWindow(Boolean.TRUE);
req.setDownloadResult(Boolean.TRUE);
RPCManager.sendRequest(req);

I am returning HTML in the response and wanted it to appear in a new tab or browser window. I see the request is received by my servlet and the servlet returns a response but no browser window is opened. Just for grins I tried the

RPCManger.sendRequest(req, new DSCallback()) method and it showed the callback was getting invoked. So I must still be missing a necessary setting.

Using the Developer Console I see the following when tracking the RPC
Request:
actionURL="/myapp/showData?mydata=var1"
"showPrompt", false,
"transport","xmlHttpRequest",
"useSimpleHttp", "true",
"promptStyle","cursor",
"httpMethod","POST"

Response:
the html data I returned from my servlet.

So the round trip was successful but the window did not popup. I allow popups from my browser. I tried in both FireFox and IE with no luck.