The dreaded File xxx cannot be opened for writing. error

[Florian]

I'm closing this here, follow-up discussion happens here:

File xxx cannot be opened for writing

I am getting this error on many FLAC files. But both Tag&Rename and VLC can edit the tags, and their saving the tag then makes the tag editable in Mp3tag. Mp3tag should be as tolerant of whatever this error is as the other programs.