Yes I guess s.newave has a very good point - focus is already kept when using alt + left/right. Once you are using the arrow keys (without alt) to navigate, to me it seems clear you do not _want_ to type in any filterstrings, therefore focus should be kept in the list, not in the editbox. Other than that, it's great that you keep fixing these newly discovered issues mouser!
Hmm, I might have used [email protected] as username, instead of simply username (my screenshot says '[email protected]@gmail.com' (username is blanked out)). Anyway, I also put your attached file in the plugins\FARRGoogleCalendar folder and now it works, so I guess that .dll file is required. Please include it as part of the plugin :)