I'm a Xerte newbie, so please forgive me if there's already a simple way to do this, but...
I'd find it really handy to have a search function which allowed me to search all the text which is visible to the user, for proof-reading or updating purposes.
For example, if we decided to remove or re-name part of our resource (such as re-naming 'Recommended Resources' to 'Further Reading'), it would be much easier to make sure we also updated any references to / mentions of that part if we could use a search tool to find them rather than having to read the entire resource.