Etna is new XML editor developed by Disruptive Innovations for the Connexions Project at Rice University in Houston, Texas. Based on Gecko, the layout engine of Mozilla Firefox, and RELAX NG, Etna needs very little XML knowledge from users and tries to offer an non-intrusive editing environement where UI-friendliness is the key. Because wysiwygness and UI-friendliness have almost never been the keys in the XML world, we needed to solve technical problems that DTD, XML Schema or RELAX NG cannot solve. What is the “blank” document for a given schema ? How do you associate a special stylesheet for editing to a schema ? How do you attach a localizable description or short description to an element’s name ? And so on. If these problems are old and were already discussed for SGML and DTDs back in 1992, they’re still unresolved. After a short presentation of Etna as a project, we will detail our implementation, how we extended Gecko for XML editing and how we implemented our own schema-like features to move all editing complexity from Authors to Implementors.