The Key filter (working again in 1.1.5) filters on the leading substring only. For example, when I select key 'D' I also get 'Db', 'D#', 'Dm', and so on. Since all these can be simultaneously selected for filtering the current behaviour looks like a bug to me.
The key filtering is text based and just looks for a song whose key field contains the given text. There are no restrictions on what values can be entered for Key (you could enter Z# if you wanted to). Due to this, searching for "D" will result in anything that matches D as you described. If filtering on just one key is desired, it's probably better to use the Keys dropdown.
06-03-2015, 05:03 PM (This post was last modified: 06-03-2015, 05:03 PM by Zubersoft.)
Just fixed this - the filtered list now reflects only what you've chosen and the filtering is much faster (major improvements to the filtering algorithm).