Filtering on filename extension

I have a feature suggestion:

An easy and quick way to filter the list on encoding types (filename extensions, .mp3, .ogg, .wma, .flac, .m4a, etc).

Right now, I use filtering on _PATH, but it is not simple (I have to type the extension every time I want to change it--I would prefer a toggle or action) and I cannot combine it with other filters (e.g. filtering on %artist% at the same time).

You may try to filter e. g. mp3 files:
Filter: .mp3$

A combination of sorting and filtering may give proper sets of files to work on.