'set as default track' leaves other 'default track' flags unchanged
Original reporter: mbunkus
If someone marks a track s the default track and then later selects another track of the same kind (audio, video, subs) as the default track then mmg should clear the previous flags automatically. mkvmerge will throw a warning in this case, but this should really be handled on the GUI level.
Reported by someone on forum.d9.org