How difficult would it be to implement Search within Search functionality? Sometimes it is preferable to limit subsequent searches to the result list or a subset of the result list.

This is how it is defined in FileLocator:

1) Search Result List - Searches all files listed in the result list.

2) Search Current Selection - Searches all files that are currently selected in the result list.

Search within search can work by creating a new search and pre-filling Include Files field with all the files to be searched.