I don't know about anyone else, but I find this really counter-intuitive.
I expect that when I type in the search bar, the search will be performed on current list. So, you've used panes or tree and have a bunch of files on display and to me, it seems logical that then typing into "search here" will search through that bunch of files.
I only know that the search bar comes first from reading posts on Interact, it's not really obvious from within MC itself.
For a long time after this was changed, I would still use the search bar in the way that I describe, and then I would curse a little when the goofy results reminded me of the pecking order. Surely new users will be like "wtf??" and move along in a confused state. If I wanted the search bar to search the entire library, I just make sure that the media library node was selected before typing my search.
-marko
Listening to: 'Chimes of Freedom' from 'Assorted Dylan Tracks' by 'Bob Dylan' on Media Center 9.1