I was presenting issues and problem to Florian by email, but I think it is good to share it here so I can understand if other people faced same problems. The first one I want to deal with is about columns width.
Standard and user defined active columns and order are always observed but it looks like columns width are not retained between software runs.
I tried to clean configuration with
defaults delete app.mp3tag.Mp3tag Columns, started Mp3tag and choose active columns, create my custom Sort one and reordered them all. Then I restarted Mp3tag and loaded same files (just to have a references):
This is what happens, some columns are back to their default (?) width (i.e. Filename and Title) and some to previous size (i.e. Album and Artist).
I would really love an AutoResize option or button