This should work for "foreign" languages, i.e. I want to provide a possibility to extract include files from XML (XSLT) files. A good solution might be a possibility to override/augment the RefactoringSupportProvider of any language (just like the DocumentationProvider). This is a bit related to IDEADEV-10476, because it would make those refactorings offered by a RefactoringSupportProvider even more flexible.