Since version 6 with the themes Dark/Black a proportional pitch is used also with digits. It was not so in Version 5.
This results in an awful looking typeface in columns that contain digits like year, track-Length, tracknumber.
Digit 1 is very narrow, digit 0 is very wide. So the entries in the column differ in its view depending of the content and i.e. a track-number like 11 has a different width than a tracknumber 10.
Please change this to fixed pitch again as it was before in version 5.
I always used the dark-theme but with version 6 the dark and the black theme can't be used anymore.
I don't think that this awful look is intended and therefore think it is just a bug.