Eclipse is the XML editor I have been using the most to edit ForgeRock core docs, which are in DocBook 5 XML. The tag completion works for me. So does document validation.
But I am not using the default XML file validation preferences. First, I want to see all the errors, so have checked “Enable markup validation.”
Second, the core docs use XInclude so the book files include chapters and so forth with
<xinclude:include href='chap-name.xml' /> elements. Therefore, I have checked “Process XML Inclusions” as well.
Seems like “Process XML Inclusions” should be checked by default, but it is not.
Now I can right-click (or Ctrl+click) an XML file, and then run Validate from the context menu.