As the description already describes is that with DVB subtitles (the graphic ones) the location of the subtitles are incorrect with DVB subtitles.
In addition the teletext subtitles are displayes in light blue instead of white. And with the BBC when there are live transmissions the whole subtitles (DVB and teletext) are displayes very strange (first you see word by word then the whole text with DVB graphic subs and with teletext subs you see a lot of lines were words are added and nothing is deleted).