I'm not sure how much further you want to develop this plugin, as it's more than good enough already, but I'll share my ideas/requests anyway:
1) A checkbox to "auto update" search on track change.
Reason: I often use this plugin to see if I have other versions of the same track, either by the same artist or by others. Currently I have assigned a keyboard shortcut to do a search with the playing track as input. One anoyance is that I can only make a shortcut for "Search for same..." and have to pick my own custom preset from the list over and over. My preset uses %title% as pattern, but ignores everything in parenthesis (as they often contain "(live)", "(feat..)" and such). Here is the whole preset:$trim($if(%title%,$if($greater($strchr(%title%,'('),1),$substr(%title%,0,$sub($strchr(%title%,'('),1)),%title%)))
The option to make a "direct" shortcut without the "Search for same.." detour, would be useful if you don't like the "auto update" thing.
2) A "focus" feature that works for all playlists, not only the active one. Would be useful in combination with "search all playlists". If present on multiple playlists, just pick the first one or something.
3) Add "Play track" as a "Default action". Most useful if 3) is implemented, but nice even for a single playlist.
4) Make this plugin available as a panel for UI Columns. Probably most useful if musicmusic adds support for horizontal panels under the playlist. At least to me as I like to show quite a bit of information for each search results.
These are all features I would find useful, so if one or more of them can be accomplished already, please enlighten me.
I guess all of these combined could be a plugin on its own. As a panel showing a list of similar tracks only, no dropdown lists or anything.
I know so many feature requests at once probably isn't very motivating, but pick the ones you find useful, if any at all. If you decide not to implement any of these, I would still like to thank you for this great plugin, and all your work with foobar in general.
Btw: I didn't reread the this thread, and it's been a while, so I'm sorry if I have duplicated any previous requests.