I would find very useful a "search" function that can be defined thanks to xpath.
Indeed, any one could browse elements the way an XSL would do, and update the raw data.
It could be, for instance, implemented via a new menu that could lead to a dialog reusing the current "Xpath evaluator" window. Finally, instead of opening new tabs (where every match is displayed), it would hightlight the selected items and allow to browse each item just as current "find" does (that is to say, with "next" and "previous" buttons).
NB: a check box on current "XPath evaluator" could also answer to the described need... Labelling something like "Browse/hightlight results directly in current file"