At present, the redefine node in the schema editor simply shows all of its
children, and the categorized children of the redefined schema, as one set of
children. This means that complex types, elements, and simple types will all
appear together. This is inconsistent with the rest of the schema editor, which
categorizes the various types of nodes.

This will also provide a better solution to issue 84879, in that once the
children of the redefine node are categorized, their order (within each
category) can be changed.