I think this feature would be beneficial for a lot of people. What I’m thinking is something like the directories in vanilla Finder’s column view, where there is a little arrow to its left that shows a directory’s content.
Example use case: If you’re like me and have your downloads folder divided into a few subdirectories (TV, Movies, Books, etc.), instead of having each of these subdirectories in the sidebar, you can have only the downloads folder and choose the subdirectory from the drop-down menu. More economical in terms of space and one less click.
I’d like to hear what you guys think.
EDIT: There could also be an option to show only directories on the drop-down menu, as opposed to all content.