What functionality is missing? What is unsatisfying with the current situation?

  For those of us with multiple worlds it would be nice to be able to move categories from one world to another when you accidentally place it in the wrong world.  

How does this feature request address the current situation?

  I have seen/heard about some of the other world builders who have placed categories in the wrong world unwittingly.  

What are other uses for this feature request?

  This will also allow for some of the creators to move entire categories from one world to another when deciding to delete a world but wish to keep some of the categories for the new world.