bucu – Thank you for the recommended workaround. It does seem to allow clicking on items, such as system settings, which were inaccessible otherwise.
Not clear to me if this is related, or just another Tahoe oddity, but once the workaround is applied and nxserver is restarted, clicking on anything on the screen seems to have no effect UNTIL the cursor is moved (however slightly) from the point which was clicked. Then the action clicked (e.g. closing a window, clicking the back arrow, etc.) takes place as soon as the cursor is moved. A bit disconcerting, but at least the functions that were previously non-responsive can be accessed.
Thank you again…