In earlier versions of IDEA, XML files with no valid root element worked
quite well. Now they get marked with errors all over which - besides the
problem that it looks ugly - makes IDEA crawl for bigger files.
This happens since we have some fragments included in "top-level" XML
files via XML entities. These XML fragments are no valid XML files
regarding a single root element for themselves.
Personally I prefer those includes being "valid" for themselves as well,
but I cannot change all those files now. :)