Version: (using KDE KDE 3.5.8) Consider such dir structure: ~/A/ B/ x.pdf y.pdf z.pdf C/ v.pdf z1.pdf z2.pdf My current dir is A and I search for files containing "z" in filename. With this feature I would see (after applying: "limit file list to search results"). ~/A/ B/ z.pdf C/ z1.pdf z2.pdf If I would go up, to home directory I would still see all files (because search was for A, and from that point limit applies).
The "Feed to listbox" feature gives you the very same result list in one (virtual) directory. Or by implementing a tree view (Bug 314521) this would also be possible. But a static file filter for a subset of directories does not make much sense imo.