Congrats for the great program, it really rocks! I still have several ideas:
Add an option for a vertical tag field (up/below song list, at user's choice for all the guys with tiny screens like me).
If horizontal, I think the tag field could allow some more shrinking to the left (making it more narrow). To do that, Year, Track and Genre could be one below the other instead of next to each other.
Tag creation from path - f. ex. I have the following path:
F:!AUDIO & VIDEO\My Music\2. Foreign\R\Rainbow\1981 - Difficult To Cure
Can the program be made to smart-guess album - year - artist , starting right to left, if the user predefines the format? Alternatively, if 3-4 different clipboards are added (like in MS word), the user could copy the info into them, and after that fill the fields for each track simply with Ctrl+1,2,3 or any key combo.
Is it possible to add more (all available) converts - f. ex. sometimes album name is written in comments.
Another useful feature probably would be "Swap fields", f. ex. Artist and Title (again all available).
Maybe different type of capitalization (case conversion) will be good too.
a) Master Of Puppets
Master of Puppets
c) Master of puppets
d) MASTER OF PUPPETS
c) is used commonly here in BG. There could be a separate option for "The" or "the", according to personal preference.