GWT and Firefox RPC issue

I had a problem with testing an application developed with GWT, the problem was that after compilation to html/javascript a was trying to run it locally (Firefox opening an html from local file system) with RPC against remote server. But the RPC call never procceded, the reason is probably becase firefox would consider this cross-site scripting as a security issue and would not allow it. This as not problem for IE explorer as it is not concerned about security risks. However this has a simple solution, testing could be done in hosted mode and final testing of the compiled ajax application must be done after deploying the app to the server.
More about this issue at Google groups: Invocation Exception - unable to initiate the asynchronous service invocation