Yes, my theme was extending webstandard. Is there any documentation on creating rendering and which controls it needs creating for? Is rendering for the relevant controls going to be added to webstandard? (Perhaps that is intended as part of the productised release).

Please bear in mind that many corporates have their own themes which do not extend oneui and creating renderers could be beyond many XPages developers, even with the kind of instruction we would need to include in the Extension Library book. If the controls can't be used out of the box with webstandard, it could prove more prohibitive to companies that admin's security concerns were in 8.5.2 about installing the Extension Library on servers.

In this scenario I am using a corporate XPages theme based on webstandard which pre-exists implementation of the Extension Library. Oneuiv2.1 is not an option for this customer.