From the webpage:
News: BaseX 7.5 has just been released…
BaseX is a very light-weight, high-performance and scalable XML Database engine and XPath/XQuery 3.0 Processor, including full support for the W3C Update and Full Text extensions. An interactive and user-friendly GUI frontend gives you great insight into your XML documents.
Another XML editor but I mention it for its support of XQuery more than as an editor per se.
We continue to lack a standard query language for topic maps and experience with XQuery may prove informative.
Not to mention its possible role in gathering diverse data for presentation in a merged state to users.