Nice idea. I'm not sure what you mean by "file or folder" though since those lists only contain folders. But having it search recents/favorites could definitely be useful.
Would you expect the lists to be separate (so one mode for searching recents and another for favorites) or would you want them to be searched together?
I mean to find files and folders, in the lists that Dopus have like recent or favorites (for folders) but also to be able to return files recently opened or apps executed.
It would be nice at the same time to be able to define favorite files like we have for folders.