You already have fairly general-purpose tree editing right under your nose - look at GUIs for your filesystem. You can drag and drop folders and files. You can

You already have fairly general-purpose tree editing right under your nose - look at GUIs for your filesystem. You can drag and drop folders and files. You can see the hierarchy on one side of your screen, and then the contents of a single node on another. Minimizing/expanding usually works. You can rename things in-place. If you're imagining tree structures that don't map really well to this kind of GUI, then the reason your tree editor doesn't exist should be apparent.