Current:

added (Date): before, after
year (Date): is, before, after
album, comment, composer, filename, grouping, genre, key, label, remixer, song (String): contains, is, does not contain, is not
bpm (number): greater than or equal to, less than or equal to
whitelabel (boolean?): is, is not (never used this)

Need this:
Strings: >, >=, <=, < (= new), =, !=, contains, contains not (= exist)
BPM: >, >=, <=, =, != ... a little bit better (also to read) instead of greater than or equal to, less than or equal to
Date: >, >=, <=, =, != .. Current difference between added vs. year

Also Regex expressions would be nice.

Thanks!