Thanks for pointing that thread out.
Yeah, I suppose the track browser is perfectly adequate for the task, and it's something I really should use more often.
It was more just a feeling that that's what the user interface should do - it just 'feels right'.
Programmatically, it's probably a real pain though - the track browser was designed to do that, whereas the filter pane wasn't.
So I guess I just talked myself out of this idea! lol.