The first iTunes music app for Mac and Windows had an amazing feature. A user could type the name of a song, album, or artist, and in miliseconds their library would be filtered to show all of the songs that matched.
I loved this feature. Today I'v added to QM a substring search across all files that I think is unique. It focuses on clearly communicating the location and filenames of content that matches, rather than the passage in the document. I think it's clearer.