MIME entries for MP3, AAC & MP4 have changed. M4A is included in MP4.
The new kid3.desktop MimeType: MimeType=audio/mpeg;application/ogg;audio/x-flac;audio/x-flac+ogg;audio/x-vorbis+ogg;audio/x-speex+ogg;audio/x-oggflac;audio/x-musepack;audio/aac;audio/mp4;audio/x-speex;audio/x-tta;audio/x-wavpack;x-directory/normal;inode/directory;
(I couldn't find the source of this specifications and so I assume that KDE 4.4.0 have them right)
Imported from SourceForge, author: pierre_buard