While some viewer options such as the pageMode, viewMode, etc. are already exposed and configurable through code, the parameters are not. This means that the viewer will always load the report with the default report parameter values which can troublesome.

For example, I need to be able to pass a JWT to a WebServiceDataSource inside my report and I use a report parameter for doing so. This works as expected when I use a simple report viewer but when the report is loaded by the Web Report Designer, it is not possible to pass a value from the front end where the designer is initialized.