XMLmind XML Editor v5 (September 29, 2011):

XMLmind XML Editor v5 aims to be a good tool for authoring highly modular documents: DITA maps, today's DocBook modular books and tomorrow's DocBook 5.1 assemblies, Web sites comprising a large number of XHTML pages, etc.

In order to attain this goal, we have added 3 new interactive tools to XXE: the "Browse Files" tool, the "Search Files" tool and the "Document Set" tool.

These new tools are showcased in "XMLmind XML Editor v5 Primer" (which includes a 3:30 screencast).

Moreover, the "Document Set" tool has a lesson of its own in our tutorial