It looks like you can’t use the same shortcuts to rename groups or folders in tree view mode as you can in large/small icon mode. You can only right click and select rename. It isn’t a big deal, but I do love my keyboard shortcuts.
I also noticed you can’t copy selected text when renaming things using Ctrl-C.
Edit: The Ctrl-R shortcut does work in tree view.
Edit2: Same applies to delete key to try and delete a group or folder.