Hurrah! Resolution switching is much improved with the new version of Plex HTPC (1.39.1). Thankyou!
4K and HD switching seems good, but, unfortunately, there is still a problem when switching to SD resolutions. All video is forced to 16:9, so it is stretching 4:3 video to widescreen and losing the black bars. None of the zoom settings seem to do anything to correct this.
