Call I view all files in a folder structure (i.e., in all of the recursive daughter folders) in one window? Command line is good, too (I'm on Ubuntu or MacOS).
Scenario: I have a bunch of pdfs in directory, but I'd like to categorize them without losing the ability to easily browse all at once. I plan on using search, too, but it's nice to have the ability to see all of these pdfs in one list.