All you can do in file manager now is to create a new folder. That's pretty annoying. I'd like to be able to create/rename/delete files and folders, and have system context menu too.
Basic file operations will be added (to context menu as well).
As per _system_ context menu - I don't think there is an easy way to do that except for implementing that manually for each system (and for each DE for Unix-likes). Too many effort for the thing that is not meant to be a fully-featured file manager.